Low-temperature toughness properties of 500 MPa offshore steels and their simulated coarse-grained heat-affected zones

AbstractOffshore steels for cold climate conditions require not only relatively high strength to improve the cost-efficiency of the structures, but also excellent toughness at low temperatures to guarantee the safety of the structures in harsh environments. The most challenging locations to fulfil both requirements are in the welded joints of these steels because the weld thermal cycles cause irreversible changes to the steel microstructure. Titanium and niobium are often used in these steels to form nanoscale precipitates and reduce the austenite grain growth during the thermal cycle. However, there is a risk that in addition to the nanoscale precipitates formed from the solid state, microscale coarse inclusions are also formed from the melt. These inclusions are hard and brittle and thus likely to deteriorate mechanical properties such as fracture toughness and impact toughness. In this study, two experimental 500 MPa offshore steels with different carbon contents and with differing inclusion structures were studied to find out whether microscale titanium-based nitrides significantly deteriorate the impact and fracture toughness of the coarse-grained heat-affected zone (CGHAZ) of these steels at low temperatures. A Gleeble 3800 was used to simulate the CGHAZ with two different cooling rates, the fracture toughness was determined by three-point bend testing, and the impact toughness was determined by Charpy V-notch testing. The study was limited to single-pass welding scenarios. Inclusions were characterized using FESEM-EDS. It was found that both impact and fracture toughness of the steel with coarse titanium-based nitrides were lower and the scatter higher than in the steel with a higher quantity of calcium-based inclusions and without the coarse nitrides. Fractographic examination showed that the failure in the samples with the lowest toughness was initiated by the coarse titanium-niobium nitrides. Thus, to avoid CGHAZ brittleness under cold conditions, it is necessary to mitigate the formation of coarse nitrides by careful control of steelmaking process and continuous casting to avoid the segregation of titanium, niobium and nitrogen.Abstract Offshore steels for cold climate conditions require not only relatively high strength to improve the cost-efficiency of the structures, but also excellent toughness at low temperatures to guarantee the safety of the structures in harsh environments. The most challenging locations to fulfil both requirements are in the welded joints of these steels because the weld thermal cycles cause irreversible changes to the steel microstructure. Titanium and niobium are often used in these steels to form nanoscale precipitates and reduce the austenite grain growth during the thermal cycle. However, there is a risk that in addition to the nanoscale precipitates formed from the solid state, microscale coarse inclusions are also formed from the melt. These inclusions are hard and brittle and thus likely to deteriorate mechanical properties such as fracture toughness and impact toughness. In this study, two experimental 500 MPa offshore steels with different carbon contents and with differing inclusion structures were studied to find out whether microscale titanium-based nitrides significantly deteriorate the impact and fracture toughness of the coarse-grained heat-affected zone (CGHAZ) of these steels at low temperatures. A Gleeble 3800 was used to simulate the CGHAZ with two different cooling rates, the fracture toughness was determined by three-point bend testing, and the impact toughness was determined by Charpy V-notch testing. The study was limited to single-pass welding scenarios. Inclusions were characterized using FESEM-EDS. It was found that both impact and fracture toughness of the steel with coarse titanium-based nitrides were lower and the scatter higher than in the steel with a higher quantity of calcium-based inclusions and without the coarse nitrides. Fractographic examination showed that the failure in the samples with the lowest toughness was initiated by the coarse titanium-niobium nitrides. Thus, to avoid CGHAZ brittleness under cold conditions, it is necessary to mitigate the formation of coarse nitrides by careful control of steelmaking process and continuous casting to avoid the segregation of titanium, niobium and nitrogen

Detrimental Effect of Coarse Titanium-Niobium Nitrides on the Fracture Toughness of the CGHAZ in a 500 MPa Offshore Steel for Cold Climate Conditions

AbstractOffshore steels for cold climate conditions require not only relatively high strength to improve the cost-efficiency of the structures, but also excellent toughness at low temperatures to guarantee the safety of the structures in harsh environments. The most challenging locations to fulfil both requirements are in the welded joints of these steels because the weld thermal cycles cause detrimental changes to the steel microstructure. Titanium and niobium are often used in these steels to form nanoscale precipitates and reduce austenite grain growth during the thermal cycle. However, there is a risk that in addition to the nanoscale precipitates formed from the solid state, microscale coarse inclusions are also formed from the melt. These inclusions are hard and brittle and thus likely to deteriorate mechanical properties such as fracture toughness and impact toughness. In this study, two experimental 500 MPa offshore steels with differing inclusion structures were studied to find out if titanium based nitrides significantly deteriorate the fracture toughness of the coarse grained heat-affected zone (CGHAZ) at -40 °C. A Gleeble 3800 was used to simulate the CGHAZ, and the fracture toughness was determined by three point bending testing. Inclusions were characterized using FESEM-EDS. It was found that fracture toughness of the steel with coarse nitrides was lower and the scatter higher than in the steel with a higher calcium based inclusion content and without the coarse nitrides. Fractographic examination showed that the failure in the samples with the lowest toughness was initiated by coarse titanium-niobium nitrides. To avoid toughness problems caused by the CGHAZ under cold conditions, it is necessary to prevent the formation of coarse nitrides during steel production.Abstract Offshore steels for cold climate conditions require not only relatively high strength to improve the cost-efficiency of the structures, but also excellent toughness at low temperatures to guarantee the safety of the structures in harsh environments. The most challenging locations to fulfil both requirements are in the welded joints of these steels because the weld thermal cycles cause detrimental changes to the steel microstructure. Titanium and niobium are often used in these steels to form nanoscale precipitates and reduce austenite grain growth during the thermal cycle. However, there is a risk that in addition to the nanoscale precipitates formed from the solid state, microscale coarse inclusions are also formed from the melt. These inclusions are hard and brittle and thus likely to deteriorate mechanical properties such as fracture toughness and impact toughness. In this study, two experimental 500 MPa offshore steels with differing inclusion structures were studied to find out if titanium based nitrides significantly deteriorate the fracture toughness of the coarse grained heat-affected zone (CGHAZ) at -40 °C. A Gleeble 3800 was used to simulate the CGHAZ, and the fracture toughness was determined by three point bending testing. Inclusions were characterized using FESEM-EDS. It was found that fracture toughness of the steel with coarse nitrides was lower and the scatter higher than in the steel with a higher calcium based inclusion content and without the coarse nitrides. Fractographic examination showed that the failure in the samples with the lowest toughness was initiated by coarse titanium-niobium nitrides. To avoid toughness problems caused by the CGHAZ under cold conditions, it is necessary to prevent the formation of coarse nitrides during steel production

The Effect of Composition and Hot Rolling on the Microstructure and Mechanical Properties of Wear Resistant Steels

AbstractThe effect of microstructure on the mechanical properties of three thermomechanically rolled and direct quenched wear resistant steel plates was investigated. The prior austenite morphology and transformed microstructure was studied and compared to tensile properties and impact toughness. Decreasing the finishing rolling temperature increased the level of austenite pancaking. Centerlines of samples consisted mainly of auto-tempered martensite. With lower finishing rolling temperatures and higher reductions in the non-recrystallization regime the formation of polygonal ferrite and bainite increased at the quarter thickness. High fraction of polygonal ferrite seemed to have a detrimental effect on strength and impact toughness. Impact toughness is also impaired by the presence of coarse inclusions.Abstract The effect of microstructure on the mechanical properties of three thermomechanically rolled and direct quenched wear resistant steel plates was investigated. The prior austenite morphology and transformed microstructure was studied and compared to tensile properties and impact toughness. Decreasing the finishing rolling temperature increased the level of austenite pancaking. Centerlines of samples consisted mainly of auto-tempered martensite. With lower finishing rolling temperatures and higher reductions in the non-recrystallization regime the formation of polygonal ferrite and bainite increased at the quarter thickness. High fraction of polygonal ferrite seemed to have a detrimental effect on strength and impact toughness. Impact toughness is also impaired by the presence of coarse inclusions

Dental caries is associated with lower respiratory tract infections : A population-based cohort study

AbstractIntroduction: Dental caries and respiratory tract infections are among the most common infectious diseases worldwide and they both are appearing in the respiratory system. However, their relations are still unclear. This study investigated the association of dental caries on the risk of lower respiratory tract infections (LRTI) in young adulthood.Methods: The study population consisted of 1,592 Finnish young adults participating in the 20-year follow-up of The Espoo Cohort Study. The information on the occurrence of LRTIs (pneumonia or acute bronchitis) during the preceding 12 months was based on the follow-up questionnaire and the National Hospital Discharge Register. Lifelong caries on permanent teeth was defined as a self-reported number of filled teeth (FT). The risk ratios (RR) of LRTIs with 95% confidence intervals (CI) were estimated using Poisson regression models.Results: High FT number was associated with an increased occurrence of LRTIs with an adjusted RR of 1.24 per interquartile range (IQR) of FT (95% CI 1.06–1.44). The risk of LRTIs increased according to the increasing number of FTs, being highest among those subjects with 10 or more filled teeth (adjusted RR 2.30; 1.27–4.17). Family’s socioeconomic status or smoking did not modify the effect.Conclusions: Our results suggest that dental caries increases the risk of LRTIs. We did not find any significant effect modification by shared determinants of caries and LRTIs. However, it is possible, that common risk factors might explain at least partly the observed relation between FT and LRTIs or that the causality is bidirectional.Abstract Introduction: Dental caries and respiratory tract infections are among the most common infectious diseases worldwide and they both are appearing in the respiratory system. However, their relations are still unclear. This study investigated the association of dental caries on the risk of lower respiratory tract infections (LRTI) in young adulthood. Methods: The study population consisted of 1,592 Finnish young adults participating in the 20-year follow-up of The Espoo Cohort Study. The information on the occurrence of LRTIs (pneumonia or acute bronchitis) during the preceding 12 months was based on the follow-up questionnaire and the National Hospital Discharge Register. Lifelong caries on permanent teeth was defined as a self-reported number of filled teeth (FT). The risk ratios (RR) of LRTIs with 95% confidence intervals (CI) were estimated using Poisson regression models. Results: High FT number was associated with an increased occurrence of LRTIs with an adjusted RR of 1.24 per interquartile range (IQR) of FT (95% CI 1.06–1.44). The risk of LRTIs increased according to the increasing number of FTs, being highest among those subjects with 10 or more filled teeth (adjusted RR 2.30; 1.27–4.17). Family’s socioeconomic status or smoking did not modify the effect. Conclusions: Our results suggest that dental caries increases the risk of LRTIs. We did not find any significant effect modification by shared determinants of caries and LRTIs. However, it is possible, that common risk factors might explain at least partly the observed relation between FT and LRTIs or that the causality is bidirectional

Genetic predictors of lifelong medication-use patterns in cardiometabolic diseases

Peer reviewe

Hypothermia following antipsychotic drug use

Objective: Hypothermia is an adverse drug reaction (ADR) of antipsychotic drug (APD) use. Risk factors for hypothermia in ADP users are unknown. We studied which risk factors for hypothermia can be identified based on case reports. Method: Case reports of hypothermia in APD-users found in PUBMED or EMBASE were searched for risk factors. The WHO international database for Adverse Drug Reactions was searched for reports of hypothermia and APD use. Results: The literature search resulted in 32 articles containing 43 case reports. In the WHO database, 480 reports were registered of patients developing hypothermia during the use of APDs which almost equals the number of reports for hyperthermia associated with APD use (n=524). Hypothermia risk seems to be increased in the first days following start or dose increase of APs. APs with strong 5-HT2 antagonism seem to be more involved in hypothermia; 55% of hypothermia reports are for atypical antipsychotics. Schizophrenia was the most prevalent diagnosis in the case reports. Conclusion: Especially in admitted patients who are not able to control their own environment or physical status, frequent measurements of body temperature (with a thermometer that can measure low body temperatures) must be performed in order to detect developing hypothermia

Overlap of genetic loci for central serous chorioretinopathy with age-related macular degeneration

IMPORTANCE Central serous chorioretinopathy (CSC) is a serous maculopathy of unknown etiology. Two of 3 previously reported CSC genetic risk loci are also associated with AMD. Improved understanding of CSC genetics may broaden our understanding of this genetic overlap and unveil mechanisms in both diseases.OBJECTIVE To identify novel genetic risk factors for CSC and compare genetic risk factors for CSC and AMD.DESIGN, SETTING, AND PARTICIPANTS Using International Classification of Diseases, Ninth (ICD-9) and Tenth (ICD-10) Revision code-based inclusion and exclusion criteria, patients with CSC and controls were identified in both the FinnGen study and the Estonian Biobank (EstBB). Also included in ameta-analysis were previously reported patients with chronic CSC and controls. Data were analyzed from March 1 to September 31, 2022.MAIN OUTCOMES AND MEASURES Genome-wide association studies (GWASs) were performed in the biobank-based cohorts followed by ameta-analysis of all cohorts. The expression of genes prioritized by the polygenic priority score and nearest-gene methods were assessed in cultured choroidal endothelial cells and public ocular single-cell RNA sequencing data sets. The predictive utility of polygenic scores (PGSs) for CSC and AMD were evaluated in the FinnGen study.RESULTS A total of 1176 patients with CSC and 526 787 controls (312 162 female [59.3%]) were included in this analysis: 552 patients with CSC and 343 461 controls were identified in the FinnGen study, 103 patients with CSC and 178 573 controls were identified in the EstBB, and 521 patients with chronic CSC and 3577 controls were included in ameta-analysis. Two previously reported CSC risk loci were replicated (near CFH and GATA5) and 3 novel loci were identified (near CD34/46, NOTCH4, and PREX1). The CFH and NOTCH4 loci were associated with AMD but in the opposite direction. Prioritized genes showed increased expression in cultured choroidal endothelial cells compared with other genes in the loci (median [IQR] of log 2 [counts per million], 7.3 [0.6] vs 4.7 [3.7]; P =.004) and were differentially expressed in choroidal vascular endothelial cells in single-cell RNA sequencing data (mean [SD] fold change, 2.05 [0.38] compared with other cell types; P < 7.1 x 10(-20)). A PGS for AMD was predictive of reduced CSC risk (odds ratio, 0.76; 95% CI, 0.70-0.83 per +1 SD in AMD-PGS; P = 7.4 x 10(-10)). This association may have been mediated by loci containing complement genes.CONCLUSIONS AND RELEVANCE In this 3-cohort genetic association study, 5 genetic risk loci for CSC were identified, highlighting a likely role for genes involved in choroidal vascular function and complement regulation. Results suggest that polygenic AMD risk was associated with reduced risk of CSC and that this genetic overlap was largely due to loci containing complement genes.Ophthalmic researc

Overlap of genetic loci for central serous chorioretinopathy with age-related macular degeneration (vol. 141, pg. 499, 2023)

Ophthalmic researc

A second update on mapping the human genetic architecture of COVID-19

Matters Arising From: COVID-19 Host Genetics Initiative. Nature https://doi.org/10.1038/s41586-021-03767-x (2021)Data availability: Summary statistics generated by the COVID-19 HGI are available online, including per-ancestry summary statistics for African, admixed American, East Asian, European and South Asian ancestries (https://www.covid19hg.org/results/r7/). The analyses described here used the data release 7. If available, individual-level data can be requested directly from contributing studies, listed in Supplementary Table 1. We used publicly available data from GTEx (https://gtexportal.org/home/), the Neale laboratory (http://www.nealelab.is/uk-biobank/), the Finucane laboratory (https://www.finucanelab.org), the FinnGen Freeze 4 cohort (https://www.finngen.fi/en/access_results) and the eQTL catalogue release 3 (http://www.ebi.ac.uk/eqtl/).Code availability: The code for summary statistics lift-over, the projection PCA pipeline including precomputed loadings and meta-analyses (https://github.com/covid19-hg/); for heritability estimation (https://github.com/AndrewsLabUCSF/COVID19_heritability); for Mendelian randomization and genetic correlation (https://github.com/marcoralab/MRcovid); and subtype analyses (https://github.com/mjpirinen/covid19-hgi_subtypes) are available at GitHub.Reporting summary: Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article online at: https://www.nature.com/articles/s41586-023-06355-3#MOESM2 .Supplementary information is available online at: https://www.nature.com/articles/s41586-023-06355-3#Sec4 .Copyright © The Author(s) 2023. Investigating the role of host genetic factors in COVID-19 severity and susceptibility can inform our understanding of the underlying biological mechanisms that influence adverse outcomes and drug development1,2. Here we present a second updated genome-wide association study (GWAS) on COVID-19 severity and infection susceptibility to SARS-CoV-2 from the COVID-19 Host Genetic Initiative (data release 7). We performed a meta-analysis of up to 219,692 cases and over 3 million controls, identifying 51 distinct genome-wide significant loci—adding 28 loci from the previous data release2. The increased number of candidate genes at the identified loci helped to map three major biological pathways that are involved in susceptibility and severity: viral entry, airway defence in mucus and type I interferon