| 1. |
- Bjurman, Christian, 1983, et al.
(författare)
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Cystatin C in a composite risk score for mortality in patients with infective endocarditis: a cohort study
- 2012
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To develop a multimarker prognostic score for infective endocarditis (IE). DESIGN: Retrospective case-control. SETTING: Secondary care. Single centre. PARTICIPANTS: 125 patients with definite IE. PRIMARY OUTCOME MEASURES: 90-day and 5-year mortality. RESULTS: Mean age was 62.7+/-17 years. The 90-day and 5-year mortality was 10.4% and 33.6%, respectively. CysC levels at admission and over 20% increases in CysC levels during 2 weeks of treatment were prognostic for 90-day and 5-year mortality independent of creatinine estimated glomerular filtration rate. In multivariate analyses, CysC (OR 5.42, 95% CI 1.90 to 15.5, p=0.002) and age (OR 1.06, 95% CI 1.02 to 1.10, p=0.002) remained prognostic for 5-year mortality. NT-proBNP, TnT, C reactive protein and interleukin 6 were also linked to prognosis. A composite risk scoring system using levels of CysC, NT-proBNP, age and presence of mitral valve insufficiency was able to separate a high-risk and a low-risk group. CONCLUSIONS: CysC levels at admission and increase in CysC after 2 weeks of treatment were independent prognostic markers for both 90-day and 5-year mortality in patients with IE. A multimarker composite risk scoring system including CysC identified a high-risk group.
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| 2. |
- Bjurman, Christian, 1983, et al.
(författare)
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Decreased admissions and hospital costs with a neutral effect on mortality following lowering of the troponin T cutoff point to the 99th percentile
- 2017
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Ingår i: Cardiology journal. - 1897-5593 .- 1898-018X. ; 24:6, s. 612-622
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Tidskriftsartikel (refereegranskat)abstract
- Background: The implementation of high-sensitivity cardiac troponin T (hs-cTnT) assays and a cutoff based on the 99th cTnT percentile in the evaluation of patients with suspected acute coronary syndrome has not been uniform due to uncertain effects on health benefits and utilization of limited resources.Methods:Clinical and laboratory data from patients with chest pain or dyspnea at the emergency department (ED) were evaluated before (n = 20516) and after (n = 18485) the lowering of the hs-cTnT cutoff point from 40 ng/L to the 99th hs-cTnT percentile of 14 ng/L in February 2012. Myocardial infarction (MI) was diagnosed at the discretion of the attending clinicians responsible for the patient.Results:Following lowering of the hs-cTnT cutoff point fewer ED patients with chest pain or dyspnea as the principal complaint were analyzed with an hs-cTnT sample (81% vs. 72%, p < 0.001). Overall 30-day mortality was unaffected but increased among patients not analyzed with an hs-cTnT sample (5.3% vs. 7.6%, p < 0.001). The MI frequency was unchanged (4.0% vs. 3.9%, p = 0.72) whereas admission rates decreased (51% vs. 45%, p < 0.001) as well as hospital costs. Coronary angiographies were used more frequently (2.8% vs. 3.3%, p = 0.004) but with no corresponding change in coronary interventions.Conclusions:At the participating hospital, lowering of the hs-cTnT cutoff point to the 99th percentile decreased admissions and hospital costs but did not result in any apparent prognostic or treatment benefits for the patients.
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| 3. |
- Bjurman, Martin, et al.
(författare)
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Fracture mechanical testing of in service thermally aged cast stainless steel
- 2016
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Ingår i: Fatigue and Fracture Test Planning, Test Data Acquisitions and Analysis. - : ASTM International. - 9780803176393 ; , s. 58-80
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Konferensbidrag (refereegranskat)abstract
- Embrittlement of Duplex Stainless Steels by thermal aging shortens the service life of structural components in Light Water Reactors (LWRs). This is an important issue when life extension programs are aiming at 60-80 years in service, as ductile failure is a design prerequisite. Cast and welded austenitic stainless steels, which contain some ferrite, are known to be affected by thermal aging. Historically, many LWR components of complex geometry have been cast in the Mo-containing quality CF8M. Aging is mainly attributed to two types of phase transformations occurring within the minor ferritic phase; Demixing of the ferrite by spinodal decomposition into Cr-rich a´ and Fe-rich a regions; and precipitation of G-phase, carbides and other secondary phases.The present program of two in-service aged pipe bend castings from the Pressurized Water Reactor (PWR) Ringhals 2 Steam Generator. These components are large castings of stainless steel quality CF8M. The manufacturing process produces a non-uniform microstructure with coarse ferrite and a high degree of directionality affecting properties as well as the methodology for testing.The materials were exposed to primary circuit PWR water for 72 kh at 291ºC and 325ºC, respectively, followed by 22 kh at a reduced service temperature.Fracture mechanical evaluation using the J-R technique at RT and 300ºC as well as instrumented Charpy-tests ranging from -196ºC to +400ºC are conducted. Effects of large microstructural heterogeneity and anisotropy from the casting and heat treating processes are tested and evaluated. The change of these parameters effect on aging embrittlement and fracture mechanisms within each phase as well as phase interaction are also studied.
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| 4. |
- Bjurman, Martin, et al.
(författare)
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Localized Deformation Behaviour of Thermally Aged Stainless Steel Castings
- 2014
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Ingår i: Fontevraud 8 - Contribution of Materials Investigations and Operating Experience to LWRs’ Safety, Performance and Reliability. - : SFEN.
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Konferensbidrag (refereegranskat)abstract
- Thermal ageing effects on the properties of structural materials in Light Water Reactors, is an increasingly important issue when life extension programs are aiming at 60-80 years in service. Thermal ageing of cast and welded austenitic stainless steels containing some δ−ferrite is well known and various fracture mechanics methods have been used to quantify mechanical property evolution. Thermal aging largely affects the δ−ferritic phase and often causes a change of fracture from δ−ferrite cleavage initiation to δ−ferrite to austenite phase boundary decohesion.The objective of the present work is to investigate deformation behaviour of the two phases in cast austenitic stainless steel (CASS). This is a part of a larger effort of testing and modelling the small scale deformation and cracking mechanistics of aged solidification structures in Austenitic SS. The combined effects of thermal ageing, deformation rate and temperature on the local deformation are investigated. Focus is on the stress and strain states of the phase boundary regions and effect of phase structure. Tensile tests are conducted followed by microstructural evaluation using hardness measurements, metallography and SEM/EBSD-analysis.It is seen that the effect of thermal ageing on tensile properties of the tested CF8M material is significant. The YS, UTS increase and fracture strain decreases with increased thermal ageing.A strain rate sensitivity is seen and increases and changes mode with ageing, mainly attributed to the austenite’s change of deformation mechanistics, indicating the importance of including austenite ageing in the evaluation of mechanical changes. Strain appears to be more localized when increasing the deformation rate for the highly aged state. The ferrites tendency to deform over fracture increases with strain rate.
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| 5. |
- Bjurman, Martin, et al.
(författare)
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Microstructural evolution of welded stainless steels on integrated effect of thermal aging and low flux irradiation
- 2019
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Ingår i: Minerals, Metals and Materials Series. - : Springer International Publishing. - 2367-1696 .- 2367-1181. ; Part F11, s. 703-710
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Konferensbidrag (refereegranskat)abstract
- The combined effect of thermal aging and irradiation on cast and welded stainless steel solidification structures is not sufficiently investigated. From theory and consecutive aging and irradiation experiments, the effect of simultaneous low rate irradiation and thermal aging is expected to accelerate and modify the aging processes of the ferrite phase. Here, a detailed analysis of long-term aged material at very low fast neutron flux at LWR operating temperatures using Atom Probe Tomography is presented. Samples of weld material from various positions in the core barrel of the Zorita PWR are examined. The welds have been exposed to 280–285 °C for 38 years at three different neutron fluxes between 1 × 10 −5 and 7 × 10 −7 dpa/h to a total dose of 0.15–2 dpa. The aging of the ferrite phase occurs by spinodal decomposition, clustering and precipitation of e.g. G-phase. These phenomena are characterized and quantitatively analyzed in order to understand the effect of flux in combination with thermal aging.
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| 6. |
- Bjurman, Martin, et al.
(författare)
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Microstructural evolution of welded stainless steels on integrated effect of thermal aging and low flux irradiation
- 2019
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Ingår i: Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. - Cham : Springer International Publishing. ; , s. 1919-1926
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Konferensbidrag (refereegranskat)abstract
- The combined effect of thermal aging and irradiation on cast and welded stainless steel solidification structures is not sufficiently investigated. From theory and consecutive aging and irradiation experiments, the effect of simultaneous low rate irradiation and thermal aging is expected to accelerate and modify the aging processes of the ferrite phase. Here, a detailed analysis of long-term aged material at very low fast neutron flux at LWR operating temperatures using Atom Probe Tomography is presented. Samples of weld material from various positions in the core barrel of the Zorita PWR are examined. The welds have been exposed to 280–285 °C for 38 years at three different neutron fluxes between 1 × 10 −5 and 7 × 10 −7 dpa/h to a total dose of 0.15–2 dpa. The aging of the ferrite phase occurs by spinodal decomposition, clustering and precipitation of e.g. G-phase. These phenomena are characterized and quantitatively analyzed in order to understand the effect of flux in combination with thermal aging.
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| 7. |
- Bjurman, Martin, et al.
(författare)
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Phase separation study of in-service thermally aged cast stainless steel – atom probe tomography
- 2015
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Ingår i: International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. - : Canadian Nuclear Society (CNS). - 9781510813953
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Konferensbidrag (refereegranskat)abstract
- Embrittlement of Duplex Stainless Steels by thermal aging shortens the service life of structural components in LWRs. This is an important issue when life extension programs are aiming at 60-80 years in service. Cast and welded austenitic stainless steels, which contain some ferrite, are known to be affected by thermal aging. Historically, many LWR components of complex geometry have been cast in the Mo-containing quality CF8M. Aging is attributed to two types ofphase transformations; Demixing of the ferrite by spinodal decomposition into Cr-rich ´ and Fe-rich regions; and precipitation of G-phase, carbides and other secondary phases.A study was conducted on two in-service aged large casting CF8M elbows exposed for 72 kh at 291ºC and 325ºC, respectively, followed by 22 kh at a reduced service temperature. Atom Probe Tomography was used to characterize the decomposition of the ferrite for both aging states. Spinodal decomposition and nucleation of precipitates, i.e. G-phase, have been identified. The extent of phase transformation increases with exposure temperature, and the mechanical properties follow the same trend.
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| 8. |
- Chen, Jiaxin, et al.
(författare)
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Microstructures of oxide films formed in alloy 182 BWR core shroud support leg cracks
- 2018
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Ingår i: Miner. Met. Mater. Ser.. - Cham : Springer International Publishing. - 9783319684536 ; Part F11, s. 417-431
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Konferensbidrag (refereegranskat)abstract
- This paper contributes to a TEM examination on the oxide films formed at three locations along a crack path in Alloy 182 weld from a BWR core shroud support leg, namely, the crack mouth, the midway between the mouth and the crack tip, and the crack tip. In the crack mouth the oxide film was approximately 1.6 μm in thickness and consisted of relatively pure NiO. The midway oxide film was mainly a nickel chromium oxide with a film thickness of 0.3 μm. At the crack tip the oxide film was a nickel chromium iron oxide with a film thickness of 30 nm. In all studied locations the main oxides had the similar rocksalt structure and the cracks were much wider than the thicknesses of the oxide films. It probably suggests that the corroded metal was largely dissolved into the coolant. The different dissolution rates of nickel, chromium and iron cations in the oxide films are clearly displayed with the compositions of the residual oxides. The oxide stability under different redox potentials along the crack path is briefly discussed.
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| 9. |
- Chen, Jiaxin, et al.
(författare)
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Microstructures of oxide films formed in alloy 182 bwr core shroud support leg cracks
- 2019
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Ingår i: Proceedings of the 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors. - Cham : Springer International Publishing. - 9783030046385 - 9783030046392 - 9783319515403 - 9783319651354 - 9783319728520 - 9783319950211 ; , s. 1633-1647
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Konferensbidrag (refereegranskat)abstract
- This paper contributes to a TEM examination on the oxide films formed at three locations along a crack path in Alloy 182 weld from a BWR core shroud support leg, namely, the crack mouth, the midway between the mouth and the crack tip, and the crack tip. In the crack mouth the oxide film was approximately 1.6 μm in thickness and consisted of relatively pure NiO. The midway oxide film was mainly a nickel chromium oxide with a film thickness of 0.3 μm. At the crack tip the oxide film was a nickel chromium iron oxide with a film thickness of 30 nm. In all studied locations the main oxides had the similar rocksalt structure and the cracks were much wider than the thicknesses of the oxide films. It probably suggests that the corroded metal was largely dissolved into the coolant. The different dissolution rates of nickel, chromium and iron cations in the oxide films are clearly displayed with the compositions of the residual oxides. The oxide stability under different redox potentials along the crack path is briefly discussed.
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| 10. |
- Hammarsten, Ola, et al.
(författare)
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Troponinnivåer ger nu bättre hjälp vid misstänkt hjärtinfarkt - Låga nivåer kan med hög säkerhet utesluta hjärtinfarkt : nya analysmetoder ökar den medicinska säkerheten
- 2017
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 114
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Tidskriftsartikel (refereegranskat)abstract
- Assessment of troponin levels on the emergency ward Patients with myocardial infarction are at a high risk of sudden death and new cardiovascular events. For this reason, it is important to identify these patients and device treatment to reduce the risk. Patients who seek care with symptoms indicative of myocardial infarction, mainly chest pain, constitute a large proportion of patients at our emergency departments. However, only 5-10 % of these patients have myocardial infarction, whereas the majority has benign causes of their symptoms. This means that it is important not only to identify patients with myocardial infarction quickly, but also to rule out myocardial infarction and other serious disease as fast and safely as possible. With the aid of assays capable of measuring low levels of the cardiac damage biomarker troponin, so-called high-sensitive troponin assays, and several large high-quality clinical studies, myocardial infarction can now be ruled out safely and quickly. If the patient presents with a troponin T level below 5 ng/L and has a normal ECG, myocardial infarction can normally be ruled out without the need for further investigation. In this way, about 30 % of all patients who present with a suspected myocardial infarction can leave the emergency room quickly with a high degree of medical security. On the other hand, when patients present with troponin T levels above 40 ng/L, the patient should normally be admitted to the hospital. These patients are a high-risk group and constitute only 6 % of those who seek medical attention with a suspected myocardial infarction.
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| 11. |
- Lindgren, Kristina, 1989, et al.
(författare)
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Integrated effect of thermal ageing and low flux irradiation on microstructural evolution of the ferrite of welded austenitic stainless steels
- 2021
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 551
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Tidskriftsartikel (refereegranskat)abstract
- With the purpose to quantify microstructural changes with respect to ageing degradation, the microstructure of aged type 308 stainless steel welds with a ferrite content of 5-7% has been analysed using atom probe tomography. The weld metal of the core barrel of a decommissioned light water reactor, irradiated during operation of the reactor to 0.1 dpa, 1 dpa and 2 dpa at 280-285°C (231,000 h), are compared to two similar thermally aged welds. In the ferrite of the irradiated welds, there is spinodal decomposition into Cr-rich α’ and Fe-rich α, with a similar degree of decomposition for all investigated doses, amplitudes of 21-26% and wavelengths between 6 and 9 nm. The ferrite of the thermally aged material showed evidence of decomposition when aged at 325°C (an amplitude of 13-14% and wavelength of 5 nm), but not when aged at 291°C, thus the irradiation significantly increases the rate of spinodal decomposition. There is G-phase (Ni Si Mn ) precipitation in the ferrite of all the weld metals except the one that was thermally aged at the lowest temperature. After irradiation to 1 and 2 dpa, the G-phase is considerably more well developed than after 0.1 dpa or thermal ageing.
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| 12. |
- Mangafic, Samra, et al.
(författare)
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Communication in intensive care units and cardiac wards : A literature review and personal experiences
- 2019
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Ingår i: Journal of Hospital Administration. - : Sciedu Press. - 1927-6990 .- 1927-7008. ; 8:1
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Forskningsöversikt (refereegranskat)abstract
- Background: Physicians are regularly confronted with a wide range of settings requiring good communication skills. Deficient communication is the main reason for patient complaints.Methods: A literature review and personal experiences of communication techniques used by physicians in intensive care units and cardiac wards.Results: Good communication can increase medical adherence and motivate patients to life-style changes and therefore improve outcomes, resolve or prevent conflicts, increase patients’ satisfaction with offered health care, decrease anxiety and depressive symptoms, instill hope and also make hospital staff feel better. Conclusions: In this article, different models aiming at achieving optimal results in diverse communication situations are described. Healthcare leaders and medical educators should encourage physicians to use the communication techniques presented in this review to optimize the interaction with patients, relatives and colleagues.
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| 13. |
- Ognissanti, Damiano, et al.
(författare)
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Cardiac troponin T concentrations and patient-specific risk of myocardial infarction using the novel PALfx parameter
- 2019
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Ingår i: Clinical Biochemistry. - : Elsevier BV. - 1873-2933 .- 0009-9120. ; 66, s. 21-28
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Tidskriftsartikel (refereegranskat)abstract
- Myocardial infarction (MI) is more likely if the heart damage biomarker cardiac troponin T (cTnT) is elevated in a blood sample from a patient with chest pain. There is no conventional method to estimate the risk of MI at a specific cTnT concentration. The purpose of this study was to evaluate the performance of a novel method that converts cTnT concentrations to patient-specific risks of MI. Methods: Admission cTnT measurements in 15,425 ED patients from three hospitals with a primary complaint of chest pain, with or without a clinical diagnosis of MI, were Box-Cox-transformed to normality density functions to calculate the percentage with MI among patients with a given cTnT concentration, the parametric predictive value among lookalikes (PALfx). The ability of the PALfx to generate stable risk estimates of MI was examined by bootstrapping and expressed as the coefficient of variation (CV). Results: Four age and sex-specific subgroups above or below 60 years of age with distinct cTnT distributions were identified among patients without MI. The cTnT distributions across subgroups with MI were similar, allowing us to use all admissions with MI to calculate the PALfx in the four subgroups. For instance, at a baseline cTnT concentration of 7 ng/L, a female patient < 60 years would have a 0.5% risk of MI whereas a male patient > 60 years would have a 1.9% risk of MI. To assess the stability of the PALfx method we bootstrapped smaller and smaller subsets of the 15,422 ED visits. We found that 1950 patients without MI and 50 patients with MI were sufficient to limit the variation of the PALfx with a CV of 0.8–5.4%, close to the CV using the entire dataset. The MI risk estimates were similar when data from the three hospitals were used separately to derive the PALfx equations. Conclusions: The PALfx can be used to estimate the risk of MI at patient-specific cTnT concentrations with acceptable margins of error. The patient-specific risk of disease using the PALfx could complement decision limits.
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