| 1. |
- Cain, Peter A, et al.
(författare)
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Age and gender specific normal values of left ventricular mass, volume and function for gradient echo magnetic resonance imaging: a cross sectional study.
- 2009
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Ingår i: BMC medical imaging. - : Springer Science and Business Media LLC. - 1471-2342. ; 9:2
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge about age-specific normal values for left ventricular mass (LVM), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF) by cardiac magnetic resonance imaging (CMR) is of importance to differentiate between health and disease and to assess the severity of disease. The aims of the study were to determine age and gender specific normal reference values and to explore the normal physiological variation of these parameters from adolescence to late adulthood, in a cross sectional study.
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| 2. |
- Cain, Peter, et al.
(författare)
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Physiological determinants of the variation in left ventricular mass from early adolescence to late adulthood in healthy subjects
- 2005
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Ingår i: Clin Physiol Funct Imaging. - 1475-0961. ; 25:6, s. 332-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The physiological determinants of left ventricular mass (LVM) measured by cardiac magnetic resonance (CMR) imaging are not well defined as prior investigators have studied either adults or adolescents in isolation or have not strictly excluded hypertension or accounted for the effects of exercise habits, haemodynamic, demographic, or body shape characteristics. METHODS: A total of 102 healthy volunteers (12-81 years, 53 males) underwent CMR. All parameters [unstandardized and adjusted for body surface area (BSA)] were analysed according to gender and by adolescence versus adulthood (adolescents <20 years, adults > or = 20 years). The influence of haemodynamic factors, exercise, and demographic factors on LVM were determined with multivariate linear regression. Results: LVM rose during adolescence and declined in adulthood. LVM and LVMBSA were higher in males both in adults (LVM: 188 +/- 22 g versus 139 +/- 21 g, P < 0.001; LVMBSA: 94 +/- 11 g m(-2) versus 80 +/- 11 g m(-2), P < 0.001) and in adolescents when adjusted for BSA (LVM: 128 +/- 29 g versus 107 +/- 20 g, P = 0.063; LVMBSA: 82 +/- 8 g m(-2) versus 71 +/- 10 g m(-2), P = 0.025). In adults, systolic blood pressure (SBP) and self-reported physical activity increased while meridional and circumferential wall stress were constant with age. Multivariate regression analysis revealed age, gender, and BSA as the major determinants of LVM (global R2 = 0.69). CONCLUSIONS: Normal LVM shows variation over a broad age range in both genders with a rise in adolescence and subsequent decline with increasing age in adulthood despite an increase in SBP and physical activity. BSA, age, and gender were found to be major contributors to the variation in LVM in healthy adults, while haemodynamic factors, exercise, and wall stress were not.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- Manea Hedström, Minola, et al.
(författare)
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Podocytes express ADAMTS13 in normal renal cortex and in patients with thrombotic thrombocytopenic purpura
- 2007
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Ingår i: British Journal of Haematology. - : Wiley. - 0007-1048 .- 1365-2141. ; 138:5, s. 651-662
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Tidskriftsartikel (refereegranskat)abstract
- Congenital thrombotic thrombocytopenic purpura (TTP) is associated with ADAMTS13 mutations. The major site of ADAMTS13 synthesis is the liver. Expression in other tissues, and in TTP, has not been shown. In this study, ADAMTS13 protein expression was investigated in normal kidney and in renal tissue from two TTP patients, with a compound heterozygous mutation (P353L and P457L) and a homozygous mutation (4143insA). Real-time polymerase chain reaction demonstrated ADAMTS13 mRNA in normal kidney. ADAMTS13 was detected in the glomeruli and tubuli of normal and TTP kidney using anti-ADAMTS13 antibodies. In the glomeruli, expression was localised to podocytes (as demonstrated by counterstaining with two podocyte markers) and endothelium. Similar distribution was detected in the TTP kidneys. Electron microscopy detected ADAMTS13 in podocytes, endothelium and glomerular basement membrane. Cultured human podocytes expressed ADAMTS13 mRNA and protein, and podocyte lysate exhibited von Willebrand factor-cleaving activity. Mutation expression studies of the P353L and P457L mutations showed partially impaired secretion and lower activity of the secreted mutants. Impaired secretion has previously been shown for the 4143insA mutation. Podocyte-derived ADAMTS13 may offer local protection in the high-shear microcirculation of the glomerulus. The mutations in the two TTP patients studied enabled protein expression in the podocytes but affected protease secretion.
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| 7. |
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| 8. |
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Frontiers of sociology
- 2009
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Samlingsverk (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- The 37th World Congress of the IIS focused on theory and research at the forefront of sociology and the relationship between sociology and its neighbouring disciplines. This volume constitutes a sustained effort by prominent sociologists and other social scientists to assess the standing of sociology.
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| 9. |
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| 10. |
- Hedström, Erik, et al.
(författare)
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Peak CKMB and cTnT accurately estimates myocardial infarct size after reperfusion
- 2007
-
Ingår i: Scand Cardiovasc J.. - : Informa UK Limited. ; 41:1, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To find the time-to-peak for creatine kinase MB(mass) (CKMB) and cardiac troponin T (cTnT) after acute reperfusion, to compare peak and cumulative values to estimate infarct size (IS), and to evaluate clinical routine sampling for assessment of IS. DESIGN: Acute primary percutaneous coronary intervention (PCI) was performed in 38 patients with first-time myocardial infarction. In 21 patients, CKMB and cTnT were acquired before PCI and at 1.5, 3, 6, 12, 18, 24, and 48 hours thereafter. In 17 patients, clinical routine samples were acquired at arrival, and at 10 and 20 h. IS was assessed by delayed contrast-enhanced MRI (DE-MRI). RESULTS: Time-to-peak was 7.6+/-3.6 h for CKMB and 8.1+/-3.4 h for cTnT. Peak values correlated strongly to cumulative values (r(s)=0.97-0.98) as well as to DE-MRI (r(s)=0.8-0.82). Clinical routine sampling showed lower rs values (0.47-0.60). CONCLUSIONS: Peak values are likely captured if CKMB and cTnT are acquired at 3, 6, and 12 h after acute PCI. These peak values can be used to estimate myocardial infarct size after acute PCI
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| 11. |
- Hedström, Mariann, et al.
(författare)
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Accuracy of assessment of distress, anxiety, and depression by physicians and nurses in adolescents recently diagnosed with cancer
- 2006
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Ingår i: Pediatric Blood & Cancer. - : Wiley. - 1545-5009 .- 1545-5017. ; 46:7, s. 773-9
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Tidskriftsartikel (refereegranskat)abstract
- Background. As staff members prioritize medical resources forpatients, it is imperative to find out whether their assessments ofpatients’ health status agree with patients’ assessments. The degree towhich physicians and nurses can identify the distress, anxiety, anddepression experienced by adolescents recently diagnosed withcancer was examined here. Procedure. Adolescents undergoingchemotherapy (13–19 years, n¼53), physicians (n¼48), and nurses(n¼53) completed a structured telephone interview, 4–8 weeksafter diagnosis or relapse, investigating disease and treatment-relateddistress, anxiety, and depression. Results. The accuracy of staffratings of physical distress could be considered acceptable.However, problems of a psychosocial nature, which were frequentlyoverestimated, were difficult for staff to identify. Staff underestimatedthe distress caused by mucositis and worry about missing schoolmore than they overestimated distress. These aspects were some ofthe most prevalent and overall worst according to the adolescents.Both physicians and nurses overestimated levels of anxiety anddepression. Nurses tended to show higher sensitivity than physiciansfor distress related to psychosocial aspects of distress, whilephysicians tended to show higher accuracy than nurses for physicaldistress. Conclusions. Staff was reasonably accurate at identifyingphysical distress in adolescents recently diagnosed with cancerwhereas psychosocial problems were generally poorly identified.Thus, the use of staff ratings as a ‘‘test’’ to guide specific supportseems problematic. Considering that the accuracy of staff ratingsoutside a research study is probably lower, identification of andaction taken on adolescent problems in relation to cancer diagnosisand treatment need to rely on direct communication.
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| 12. |
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| 13. |
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| 14. |
- Hedström, Peter
(författare)
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Deformation and martensitic phase transformation in stainless steels
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The use of high-energy synchrotron x-rays which has enabled three- dimensional structural characterization from the nano- to the macroscopic scale, and now to the meso-scale, such as individual grains and dislocation structures, is a major scientific advance. This is the first technique with sufficient spatial resolution and penetration power to probe the local structure embedded deep within the material. This, together with good time resolution makes it suitable for investigations of e.g. phase transformations kinetics, stress-strain behaviour, and texture evolution in stainless steels. The micromechanical response of a metastable austenitic stainless steel and a duplex stainless steel during loading has been investigated by a series of high-energy x-ray diffraction experiments at the Advanced Photon Source (APS) in Argonne, IL, USA. Different measurement scales of the steels are tested, ranging from the behaviour of individual grains up to the macroscopic material behaviour. The experimental data is used as input to material models to validate and improve existing models for strain-induced martensite and mechanical properties. The x-ray investigations have revealed that autocatalytic Ü-martensite transformation is triggered by strains induced by the transformation itself in 301 and this was evidenced as bursts of Ü-martensite transformation during tensile loading. To the author's knowledge this behaviour has not been previously reported, and is of significant importance for the mechanical properties of the metastable stainless steels, since it provides strong local hardening and increases the time to neck formation. The å-martensite formation was investigated for 45 individual austenite bulk grains in 301 and the resolved shear stress was determined. Out of the 45 austenite grains probed one was observed to form å-martensite. The grain that formed å-martensite had the highest Schmid factor for the active slip system during fcc to hcp transformation. The behaviour of 301 during tensile loading at different strain rates was also investigated and it was concluded that even moderate strain rates produce adiabatic heating sufficient to suppress the martensite formation. The strain-induced martensitic transformation and the stress-strain behaviour was predicted by an extended Olson-Cohen model, finite element simulations for the temperature evolution and a radial return algorithm for the stress-strain behaviour. The measured and modelled results were in fair agreement. In addition, the phase specific stresses were measured during the experiments and these were in good agreement with the predicted results from the finite element model. Thus, it was concluded that the employed iso- work principle was a good assumption for the stress distribution between the phases. One way of tailoring the metastable austenitic stainless steels' microstructure with different phase fractions and deformation structures is by the reverse transformation from martensite to austenite. This was investigated for the cold rolled 301 steel, and the reverse transformation was observed to occur via two different mechanisms, one diffusion controlled and the other a diffusionless transformation. The onset of the diffusion reversion was about 450°C and the shear reversion became active at higher temperatures. The microstructure of shear reversed austenite consists of highly faulted austenite with an inherited lath like structure. The stress response of 15 individual austenite and ferrite grains deeply embedded in the bulk of a duplex stainless steel was measured during tensile loading. These results showed large intergranular stresses acting between grains due to grain interaction. The large intergranular stresses will have a significant effect on the two-phase behaviour during loading.
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| 15. |
- Hedström, Peter
(författare)
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Deformation induced martensitic transformation of metastable stainless steel AISI 301
- 2005
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Metastable stainless steels are promising engineering materials demonstrating good corrosion resistance and mechanical properties. Their mechanical properties are however significantly affected by the deformation induced martensitic transformation. Hence, in order to use these steels to their full potential it is vital to have profound knowledge on this martensitic phase transformation. The aim of this thesis was therefore to investigate the evolution of phase fractions, texture, microstrains and microstructure to improve the current understanding of the deformation induced martensitic transformation in AISI 301. To investigate the deformation behavior of AISI 301, in-situ high-energy x- ray diffraction during tensile loading has been performed on samples suffering different cold rolling reduction. Ex-situ transmission electron microscopy, electron back-scattered diffraction and optical microscopy were also used to characterize the microstructure at different deformation levels. The results show that parts of the austenite transforms to both ά- martensite and ε-martensite during deformation of AISI 301. The transformation behavior of ά-martensite is however completely different from the transformation behavior of ε-martensite. ε-martensite forms in a parabolic behavior, while the ά-martensite transformation can be divided in three characteristic stages. The third transformation stage of ά-martensite has previously not been reported and it is characterized by a series of rapid transformations, each of which is followed by a period of yielding without any transformation. Moreover, the lattice strain evolution in the austenite at high plastic strains was found to be oscillatory, which is correlated with the stepwise transformation of ά-martensite as well as changes in x-ray peak broadening. This behavior was also coupled with the evolution of microstructure, where a distinct banded structure consisting of slip bands and Ü-martensite was observed at low plastic strains. This banded structure was however broken at high plastic strains when the ά-martensite grew larger and formed a block- shaped morphology. These findings lead to the conclusion that the three stages of ά- martensite transformation is due to different stages of nucleation and growth. The ά-martensite will first form as small nucleus, mainly at dislocation pile-ups along slip bands. The nucleuses will grow moderately in size and the structure will become saturated with nucleuses. Hence, the only way more ά-martensite can form is by growth of the existing nucleuses. This growth is very localized and seen as bursts in the transformation curve. The oscillatory behavior observed for the lattice strains during martensite formation possibly originate when semicoherent boundaries between austenite and ά-martensite become incoherent as the ά-martensite grow large.
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| 16. |
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| 17. |
- Hedström, Peter, et al.
(författare)
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Elastic strain evolution and ε-martensite formation in individual austenite grains during in situ loading of a metastable stainless steel
- 2008
-
Ingår i: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 62:2, s. 338-340
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Tidskriftsartikel (refereegranskat)abstract
- The (hcp) ε-martensite formation and the elastic strain evolution of individual (fcc) austenite grains in metastable austenitic stainless steel AISI 301 has been investigated during in situ tensile loading up to 5% applied strain. The experiment was conducted using high-energy X-rays and the 3DXRD technique, enabling studies of individual grains embedded in the bulk of the steel. Out of the 47 probed austenite grains, one could be coupled with the formation of ε-martensite, using the reported orientation relationship between the two phases. The formation of ε-martensite occurred in the austenite grain with the highest Schmid factor for the active {111}b12¯1N slip system.
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| 18. |
- Hedström, Peter, et al.
(författare)
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Evolution of residual strains in metastable austenitic stainless steels and the accompanying strain induced martensitic transformation
- 2006
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Ingår i: Residual Stresses VII. - Uetikon-Zuerich : Trans Tech Publications Inc.. - 0878494146 ; 524-525, s. 818-826
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Konferensbidrag (refereegranskat)abstract
- The deformation behavior of metastable austenitic stainless steel AISI 301, suffering different initial cold rolling reduction, has been investigated during uniaxial tensile loading. In situ highenergy x-ray diffraction was employed to characterize the residual strain evolution and the strain induced martensitic transformation. Moreover, the 3DXRD technique was employed to characterize the deformation behavior of individual austenite grains during elastic and early plastic deformation. The cold rolling reduction was found to induce compressive residual strains in the austenite along rolling direction and balancing tensile residual strains in the -martensite. The opposite residual strain state was found in the transverse direction. The residual strain states of five individual austenite grains in the bulk of a sample suffering 2% cold rolling reduction was found to be divergent. The difference among the grains, considering both the residual strains and the evolution of these, could not be solely explained by elastic and plastic anisotropy. The strain states of the five austenite grains are also a consequence of the local neighborhood. Introduction The metastable austenitic stainless steels partially transform from the soft and ductile austenite to the hard and brittle martensite during deformation. This deformation induced martensitic transformation provides a compos...
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| 19. |
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| 20. |
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| 21. |
- Hedström, Peter, et al.
(författare)
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Interaction domains and suicides : A population-based panel study of suicides in the Stockholm metropolitan area, 1991-1999
- 2008
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Ingår i: Social Forces. - : Oxford University Press (OUP). - 0037-7732 .- 1534-7605. ; 87:2, s. 713-740
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Tidskriftsartikel (refereegranskat)abstract
- This article examines how suicides influence suicide risks of others within two interaction domains: the family and the workplace. A distinction is made between dyad-based social-interaction effects and degree-based exposure effects. A unique database including all individuals who ever lived in Stockholm during the 1990s is analyzed. For about 5.6 years on average, 1.2 million individuals are observed, and 1,116 of them commit suicide. Controlling for other risk factors, men exposed to a suicide in the family (at work) are 8.3 (3.5) times more likely to commit suicide than non-exposed men. The social-interaction effect thus is larger within the family domain; yet work-domain exposure is more important for the suicide rate because individuals are more often exposed to suicides of coworkers than family members.
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| 22. |
- Hedström, Peter, et al.
(författare)
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Introduction
- 2009
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Ingår i: Frontiers Of Sociology. - Leiden : Brill. - 9789047442462 ; , s. 1-11
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 23. |
- Hedström, Peter, et al.
(författare)
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Load partitioning and strain-induced martensite formation during tensile loading of a metastable austenitic stainless steel
- 2009
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer Science and Business Media LLC. - 1073-5623 .- 1543-1940. ; 40:5, s. 1039-1048
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Tidskriftsartikel (refereegranskat)abstract
- In-situ high-energy X-ray diffraction and material modeling are used to investigate the strain-rate dependence of the strain-induced martensitic transformation and the stress partitioning between austenite and α′ martensite in a metastable austenitic stainless steel during tensile loading. Moderate changes of the strain rate alter the strain-induced martensitic transformation, with a significantly lower α′ martensite fraction observed at fracture for a strain rate of 10−2 s−1, as compared to 10−3 s−1. This strain-rate sensitivity is attributed to the adiabatic heating of the samples and is found to be well predicted by the combination of an extended Olson–Cohen strain-induced martensite model and finite-element simulations for the evolving temperature distribution in the samples. In addition, the strain-rate sensitivity affects the deformation behavior of the steel. The α′ martensite transformation at high strains provides local strengthening and extends the time to neck formation. This reinforcement is witnessed by a load transfer from austenite to α′ martensite during loading.
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| 24. |
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| 25. |
- Hedström, Peter, et al.
(författare)
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Stepwise transformation behavior of the strain-induced martensitic transformation in a metastable stainless steel
- 2007
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Ingår i: Scripta Materialia. - : Elsevier BV. - 1359-6462 .- 1872-8456. ; 56:3, s. 213-216
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Tidskriftsartikel (refereegranskat)abstract
- In situ high-energy X-ray diffraction during tensile loading has been used to investigate the evolution of lattice strains and the accompanying strain-induced martensitic transformation in cold-rolled sheets of a metastable stainless steel. At high applied strains the transformation to α-martensite occurs in stepwise bursts. These stepwise transformation events are correlated with stepwise increased lattice strains and peak broadening in the austenite phase. The stepwise transformation arises from growth of α-martensite embryos by autocatalytic transformation.
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| 26. |
- Hedström, Peter, et al.
(författare)
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Stress state and strain rate dependence of the strain-induced martensitic transformation in a metastable austenitic stainless steel
- 2007
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Ingår i: Fundamentals of Martensite and Bainite towards Future Steels with High Performance. - Tokyo : The Iron and Steel Institute of Japan. - 9784930980632 ; , s. 171-174
-
Konferensbidrag (refereegranskat)abstract
- The strain-induced martensitic transformation in a metastable austenitic stainless steel is investigated by high-energy x-ray diffraction and material modeling. Two different deformation modes are used (cold rolling and uniaxial tensile loading) and the effect on the strain-induced martensitic transformation behavior is investigated. Moreover, three different strain rates during the uniaxial tensile loading are evaluated. The results show a sigmoidal transformation behavior of the strain-induced martensite in respect to true strain, for tensile loading. The effect of different strain rates is also clearly seen and it alters both the amount of transformed martensite and the transformation behavior. The martensite transformation is drastically decreased already at moderate strain rates such as 10-2 s-1, due to adiabatic heating of the sample. The material model used gives an accurate prediction of the strain-induced martensitic transformation behavior during tensile loading. This is valuable for further implementation of the current material model in industrial forming mulations of real components.
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| 27. |
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| 28. |
- Hedström, Peter, 1955-, et al.
(författare)
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The analytical turn in sociology
- 2009
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Ingår i: The frontiers of sociology. - Leiden : Brill Academic Publishers. - 9789004165694 ; , s. 331-342
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Bokkapitel (populärvet., debatt m.m.)
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| 29. |
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| 30. |
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| 31. |
- Hedström, Peter, et al.
(författare)
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Tocqueville and analytical sociology
- 2009
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Ingår i: Raymond Boudon. - Oxford : The Bardwell Press. - 9781905622184 ; , s. 153-172
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 32. |
- Knutsson, Axel, et al.
(författare)
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Reverse martensitic transformation and resulting microstructure in a cold rolled metastable austenitic stainless steel
- 2008
-
Ingår i: Steel Research International. - : Wiley. - 1611-3683 .- 1869-344X. ; 79:6, s. 433-439
-
Tidskriftsartikel (refereegranskat)abstract
- The reverse martensitic transformation in cold-rolled metastable austenitic stainless steel has been investigated via heat treatments performed for various temperatures and times. The microstructural evolution was evaluated by differential scanning calorimetry, X-ray diffraction and microscopy. Upon heat treatment, both diffusionless and diffusion-controlled mechanisms determine the final microstructure. The diffusion reversion from α′-martensite to austenite was found to be activated at about 450°C and the shear reversion is activated at higher temperatures with Af′ ∼600°C. The resulting microstructure for isothermal heat treatment at 650°C was austenitic, which inherits the α′-martensite lath morphology and is highly faulted. For isothermal heat treatments at temperatures above 700°C the faulted austenite was able to recrystallize and new austenite grains with a low defect density were formed. In addition, carbo-nitride precipitation was observed for samples heat treated at these temperatures, which leads to an increasing Ms-temperature and new α′-martensite formation upon cooling.
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| 33. |
- Manea Hedström, Minola, et al.
(författare)
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ADAMTS13 phenotype in plasma from normal individuals and patients with thrombotic thrombocytopenic purpura.
- 2007
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Ingår i: European Journal of Pediatrics. - : Springer Science and Business Media LLC. - 1432-1076 .- 0340-6199. ; 166:3, s. 249-257
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Tidskriftsartikel (refereegranskat)abstract
- The activity of ADAMTS 13, the von Willebrand factor cleaving protease, is deficient in patients with thrombotic thrombocytopenic purpura (TTP). In the present study, the phenotype of ADAMTS13 in TTP and in normal plasma was demonstrated by immunoblotting. Normal plasma (n=20) revealed a single band at 190 kD under reducing conditions using a polyclonal antibody, and a single band at 150 kD under non-reducing conditions using a monoclonal antibody. ADAMTS 13 was not detected in the plasma from patients with congenital TTP (n=5) by either antibody, whereas patients with acquired TTP (n=2) presented the normal phenotype. Following immunoadsorption of immunoglobulins, the ADAMTS 13 band was removed from the plasma of the patients with acquired TTP, but not from that of normal individuals. This indicates that ADAMTS13 is complexed with immunoglobulin in these patients. The lack of ADAMTS13 expression in the plasma from patients with hereditary TTP may indicate defective synthesis, impaired cellular secretion, or enhanced degradation in the circulation. This study differentiated between normal and TTP plasma, as well as between congenital and acquired TTP. This method may, therefore, be used as a complement in the diagnosis of TTP.
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| 34. |
- Mangalaraja, R.V., et al.
(författare)
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Combustion synthesis of Y2O3 and Yb-Y2O3 : Part 1: Nanopowders and their characterization
- 2008
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Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 208:1-3, s. 415-422
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Tidskriftsartikel (refereegranskat)abstract
- Nanosized yttrium oxide and ytterbium doped yttrium oxide powders were prepared by ceramic combustion techniques such as flash combustion, citrate gel decomposition and glycine combustion using urea, citric acid and glycine respectively as fuels. As synthesized precursors and calcined powders were characterized for their structural, particle size and morphology, and the optimization of calcination process by differential scanning calorimetry and thermal gravimetry. The thermal analyses together with XRD results demonstrate the effectiveness of the combustion process for the synthesis of pure phase nanocrystalline powders. Nanocrystalline pure yttria powders were obtained by the calcination of as-prepared precursors at 1100 °C for 4 h.
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| 35. |
- Mangalaraja, R.V., et al.
(författare)
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Microwave assisted combustion synthesis of nanocrystalline yttria and its powder characteristics
- 2009
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Ingår i: Powder Technology. - : Elsevier BV. - 0032-5910 .- 1873-328X. ; 191:3, s. 309-314
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Tidskriftsartikel (refereegranskat)abstract
- Microwave assisted combustion synthesis is used for fast and controlled processing of advanced ceramics. Single phase and sinter active nanocrystalline cubic yttria powders were successfully synthesized by microwave assisted combustion using the organic fuels urea, citric acid and glycine as reducing agents. The precursor powders were investigated by thermogravimetry (TG) and differential scanning colorimetry (DSC) analyses. The as-prepared precursors and the resulting oxide powders calcined at 1100 °C in oxygen atmosphere were characterized for their structure, particle size and morphology. The thermal analyses (TG/DSC), X-ray diffraction (XRD) and Fourier transform infra red (FT-IR) results demonstrate the effectiveness of the microwave assisted combustion synthesis. The scanning electron microscopy (SEM) observations show the different morphologies of as-prepared powders and transmission electron microscopy (TEM) shows the particle sizes in the range of 30-100 nm for calcined powders for different fuels. The results confirm that the homogeneous, nano scale yttria powders derived by microwave assisted combustion have high crystalline quality and the morphology of the as-prepared precursor powders depends on the nature of organic fuel used.
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| 36. |
- Mood, Carina, 1973-
(författare)
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Poor Choices? : On Social Context and the Claiming of Means-tested Benefits
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this dissertation, comprising one theoretical chapter and three self-contained empirical studies, I study how the choice to claim means-tested benefits is affected by the social context. In Chapter 1, Considering Choices, I discuss how sociological research can benefit from taking choices into account, and I review the literature on rational choice theory to assess its relevance as a tool for considering choices in sociology.In Chapter 2, Social Influence Effects on Social Assistance Recipiency, I use aggregated register data on individuals 20–25 years old in Stockholm County during the 1990’s, to study whether Social Assistance (SA) recipiency of others of the same age in the parish of residence is related to one’s own propensity to apply for such benefits: the results show that it has substantial effects on inflow to SA but only weak effects on outflow from SA.In Chapter 3, Endogenous Neighbourhood Effects on Welfare Use, I use micro-level register data to study these processes among couples in Stockholm. The results corroborate the finding that SA recipiency among people in the neighbourhood substantially affects the probability of inflow to SA recipiency at a given income standard, suggesting self-reinforcing effects of changes in the level of SA. The estimated effects on outflow are negligible.Chapter 4, Take-up Down Under: The Under-use of Means-tested Benefits in Australia, studies the choices to claim means-tested benefits in Australia. In contrast to Sweden, virtually all benefits in Australia are means-tested. I use survey panel data to estimate the general level of non-take-up of means-tested benefits among the poor, and to study the extent and causes of take-up of Parenting Payment. The results suggest that take-up of means-tested benefits is relatively high in Australia, but that groups likely to experience higher stigma, higher transaction costs, and to have less access to information have lower take-up than others.
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| 37. |
- Nordvik, Monica K., 1974-
(författare)
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Contagious Interactions : Essays on social and epidemiological networks
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation has two overall aims; to explore and develop the use of SNA in sociology, and to demonstrate that sociology has much to give to other sciences. Interdisciplinary collaboration is necessary because we do not live in a world in which subject areas are strictly isolated. Human beings are social animals, and a sociological understanding is crucial in all human-related science. The examination in this thesis of different kinds of social networks and how they affect the lives of individuals (and vice versa) will provide knowledge both in the development of methods for analyzing social networks, and in their areas specific scientific areas.Paper I-III investigates sexual networks and how the number of sexual encounters involving intercourse in combination with the number of sexual partners affects the dynamics of sexually transmitted infections (STIs). The results show that this relationship is non-linear, indicating that it may not be the individuals with the largest number of partners who have the most impact on the spread of STIs. One might also have to focus interventions on individuals who have a large number of sexual encounters involving intercourse per partner, and who have several (but not necessarily a very large number of) partners.In the fourth paper, we apply the theoretical concept of so-called small worlds to a sexual network. The spread of epidemics can be difficult to stop in such networks, and we show that the sexual network of individuals infected with chlamydia can be characterized as such.The fifth and last paper differs from the four first. In this paper, we focus on how individuals who committed suicide in Stockholm during the 1990s where connected to each other. The social-interaction exposure effect is larger for the individual within the family than at the workplace; yet work-domain exposure is more important for the overall suicide rate because individuals are more often exposed to suicides of co-workers than family members.
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| 38. |
- Oden, Magnus, et al.
(författare)
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In situ small-angle x-ray scattering study of nanostructure evolution during decomposition of arc evaporated TiAlN coatings
- 2009
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Ingår i: APPLIED PHYSICS LETTERS. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:5, s. 053114-
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Tidskriftsartikel (refereegranskat)abstract
- Small-angle x-ray scattering was used to study in situ decomposition of an arc evaporated TiAlN coating into cubic-TiN and cubic-AlN particles at elevated temperature. At the early stages of decomposition particles with ellipsoidal shape form, which grow and change shape to spherical particles at higher temperatures. The spherical particles grow at a rate of 0.18 A/degrees C while coalescing.
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| 39. |
- Terner, Mark, et al.
(författare)
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Residual stress evolution during decomposition of Ti(1-x)Al (x)N coatings using high-energy x-rays
- 2006
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Ingår i: RESIDUAL STRESSES VII. - : Transtec Publications; 1999. ; 524-525, s. 619-624, s. 619-624
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Konferensbidrag (refereegranskat)abstract
- Residual stresses and microstructural changes during phase separation in Ti33Al67N coatings were examined using microfocused high energy x-rays from a synchrotron source. The transmission geometry allowed simultaneous acquisition of x-ray diffraction data over 360 degrees and revealed that the decomposition at elevated temperatures occurred anisotropically, initiating preferentially along the film plane. The as-deposited compressive residual stress in the film plane first relaxed with annealing, before dramatically increasing concurrently with the initial stage of phase separation where metastable, nm-scale c-AlN platelets precipitated along the film direction. These findings were further supported from SAXS analyses.
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| 40. |
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| 41. |
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| 42. |
- Ukonsaari, Jan, et al.
(författare)
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Tribological studies on an eal lubricated bearing bronze - Steel pair under reciprocating sliding conditions
- 2008
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Ingår i: Tribologia. - 0780-2285. ; 27:1, s. 3-18
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Tidskriftsartikel (refereegranskat)abstract
- Boundary lubricated journal bearings are found in various applications involving oscillatory sliding conditions. Environmental adaptation of hydraulic systems includes the introduction of synthetic esters. These new environmentally adapted lubricants (EALs) have shown very good boundary lubrication performance but also condition sensitivity. This study examines an oil lubricated bronze pin on hardened steel configuration in a reciprocating friction and wear test machine. Three synthetic esters were tested with a 1 mm stroke length. Results were compared with those for a mineral oil. The tribological performance with synthetic ester lubricant can, under certain conditions, be very good. SEM-EDS and XRD surface sensitive studies indicate the formation of a soft, copper enriched outer contact layer. The layer's nature and contact mechanisms clearly affect the performance of the different lubricants.
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| 43. |
- Åberg, Yvonne, et al.
(författare)
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Social interactions and unemployment
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper is concerned with social interactions and their importance for unemployment. A theoretical model is specified in which the social and psychological costs of unemployment depend upon the unemployment level. The theoretical analysis reveals social multiplier effects, and shows that multiple unemployment equilibria may emerge. Data on all 20- to 24-year-olds living in the Stockholm metropolitan area during the 1990s are used to test key hypotheses derived from the model. The focus is on the role of neighborhood-based reference groups, and the results support the theoretical predictions: unemployment levels vary more across neighborhood-groups than what would be expected based on variation in observable characteristics, and individuals' transition rates out of unemployment appear to be strongly influenced by the unemployment level within their neighborhood-based reference groups.
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| 44. |
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