Thermomechanical fatigue of stainless steels for automotive exhaust systems

National audienceStainless steel grades are now widely used for automotive exhaust systems, in order to increase their durability. Indeed, the exhaust systems are subjected to ever more severe conditions and they include high technology components such as manifolds, catalytic converters and particle filters. This evolution is a direct consequence of the worldwide effort to decrease automotive pollutant emissions in accordance with the new environmental regulations. This paper deals with the thermomechanical fatigue (TMF) of stainless steels at high temperature, specially behaviour and damage models, and with the recent progress in the development TMF fatigue design tools using FEA related to the design of stainless steel exhaust manifolds. A numerical method is proposed for the design and the lifetime prediction of stainless steel exhaust manifold under a thermal fatigue load. It includes the modeling of manifolds submitted to the thermal cycle reproduced from motor bench tests. The identification of the constitutive law, in particular the elasto-viscoplastic model, for a wide range of temperatures, provides the most realistic stress-strain response of the structure. Finally, a dedicated damage criterion is proposed on the basis of the maximal temperature and plastic strain amplitude reached during a thermal cycle (modified-Taira model). Identification of a more general damage model on the basis of TMF tests is also discussed

A Systematic Review and Metaanalysis on the Effects of Garlic Preparations on Blood Pressure in Individuals With Hypertension

BACKGROUND Many patients prefer herbal medications to conventional drugs. Limited trial evidence suggests that garlic preparations reduce high blood pressure (BP). METHODS We searched electronic databases through March 2014 to identify all randomized controlled trials that compared a garlic preparation to placebo in hypertensive patients. Trials were required to report BP values at baseline and after a follow-up of at least 4 weeks. RESULTS Nine double-blind trials with 482 individuals fulfilled our inclusion criteria. Included trials were rather small, and the quality of the majority of included trials was moderate. Follow-up ranged from 8 to 26 weeks. All trials reported office BP measurements. Systolic BP and diastolic BP (SBP and DBP) were more effectively reduced in individuals treated with garlic preparations than in individuals treated with placebo. However, heterogeneity was high (weighted mean difference (WMD) for SBP was −9.1mm Hg; 95% confidence interval (CI), −12.7 to −5.4; P for heterogeneity = 0.0006; and I 2 = 71%; WMD for BP was −3.8mm Hg; 95% CI, −6.7 to −1.0; P for heterogeneity = 0.00001; I 2 = 80%). When analyses were restricted to higher-quality trials using intention-to-treat analysis or to trials with concealed treatment allocation and standardized and blinded BP measurement, effect sizes for SBP but not for DBP were lower and heterogeneity disappeared. CONCLUSIONS Although evidence from this review suggests that garlic preparations may lower BP in hypertensive individuals, the evidence is not strong. A well-conducted and powered trial of longer duration is needed to confirm these finding

Clinical outcomes of stents versus balloon angioplasty in non-acute coronary artery disease: A meta-analysis of randomized controlled trials

Aims To evaluate whether stents as compared to balloon angioplasty reduce mortality in patients with non-acute coronary artery disease. Methods and results We identified randomized controlled trials comparing stents to balloon angioplasty for the treatment of non-acute coronary artery disease by searching major medical databases from 1979 to March 2002. Two independent reviewers selected and extracted data from trials that had to report data on death and myocardial infarction. Nineteen trials, with a total of 8004 patients, fulfilled our inclusion criteria. For 1000 patients treated with stents rather than balloon angioplasty, 3 (95% CI 0-6), 5 (95% CI 0-9), and 6 (95% CI -1-12) additional lives were saved at 30 days, 6 and 12 months. At 12 months, for 1000 patients treated with stents rather than balloon angioplasty 46 (95% CI 25-66) additional target vessel revascularizations were avoided, but 25 (95% CI 15-34) additional bleeding complications with need for blood transfusion or surgical intervention occurred. In sensitivity analysis 11 (95% CI 2-20) and 2 (95% CI -4-7) deaths were avoided per 1000 patients treated with stents rather than PTCA in trials that routinely used compared to trials that did not use glycoprotein IIb/IIIa inhibitors. Conclusion In non-acute coronary disease stents may reduce overall mortality, but this benefit seems to be limited to stents used in conjunction with glycoprotein IIb/IIIa inhibitors. Stents compared to PTCA reduce target vessel revascularizations, but increase the risk of bleeding complication

EVIDENCE OF A GUADALUPIAN AGE FOR THE KHUFF FORMATION OF SOUTHEASTERN OMAN: PRELIMINARY REPORT

The Guadalupian succession of the Huqf area (Sultanate of Oman) represents a mega-sequence comprising the fluvial terrigenous Gharif Formation and the overlying marine Khuff Formation. The Khuff Fm. is subdivided into four members and is composed of marls and bioclastic limestones. The Khuff Fm. yields a rich fauna of brachiopods, conodonts, foraminifers, bivalves, gastropods, ostracods and cephalopods. The brachiopod fauna of the Khuff Fm. includes strophomenids, productids, orthids and terebratulids. The associated conodont fauna includes Hindeodus excavatus Behnken, Merrilina sp., M. praedivergens Kozur & Mostler, and Sweetina n. sp. (systematic descriptions of conodonts are given in the Paleontological Appendix). Foraminifers are represented by species of Miliolina and Rotaliina. The Khuff Fm. is given a Wordian age, based on brachiopods and conodonts. The depositional environment of the Khuff Fm. of southeastern Oman corresponds to the outer shelf of a large carbonate platform covering most of the Arabian Platform. The Khuff Fm. is interpreted as a major transgressive-regressive cycle related to differential subsidence.&nbsp

Clinical Outcomes of Primary Stenting versus Balloon Angioplasty in Patients with Myocardial Infarction: A Meta-analysis of Randomized Controlled Trials

PURPOSE: To examine whether primary stenting as compared with primary balloon angioplasty reduces clinical outcomes in patients with myocardial infarction. METHODS: Major medical databases from 1979 to March 2002 were searched for randomized controlled trials that compared primary stenting with balloon angioplasty in patients with myocardial infarction. Two independent reviewers selected and extracted data from identified trials. The outcomes were mortality at 30 days, 6 months, and 12 months; recurrent events; and bleeding. RESULTS: Nine trials with a total of 4433 patients fulfilled the inclusion criteria. The odds ratios for mortality after stenting as compared with balloon angioplasty were 1.17 (95% confidence interval [CI]: 0.78 to 1.74) at 30 days, 1.07 (95% CI: 0.76 to 1.52) at 6 months, and 1.09 (95% CI: 0.80 to 1.50) at 12 months (P for heterogeneity Ͼ0.1 for each comparison). The odds ratios for reinfarction after stenting as compared with balloon angioplasty were 0.52 (95% CI: 0.31 to 0.87) at 30 days, 0.67 (95% CI: 0.45 to 1.00) at 6 months, and 0.67 (95% CI: 0.45 to 0.99) at 12 months; for target vessel revascularization, they were 0.46 (95% CI: 0.34 to 0.61) at 30 days, 0.42 (95% CI: 0.35 to 0.51) at 6 months, and 0.48 (95% CI: 0.39 to 0.59) at 12 months (P for heterogeneity Ͼ0.1 for all estimates with the exception of reinfarction at 12 months where P ϭ 0.08). The odds ratio for postinterventional bleeding complications after stenting as compared with balloon angioplasty was 1.34 (95% CI: 0.95 to 1.88; P for heterogeneity Ͼ0.1). CONCLUSION: Compared with balloon angioplasty, primary stenting is not associated with lower mortality, but is associated with a lower risk of reinfarction and target vessel revascularization. Am J Med. 2004;116:253-262. ©2004 by Excerpta Medica Inc. I n patients with myocardial infarction, balloon angioplasty reduces short-term death, nonfatal myocardial infarction, and stroke when compared with thrombolytic reperfusion (1). Still, the clinical efficacy of balloon angioplasty is limited by the development of late restenosis in up to 50% of patients, and by recurrent myocardial infarction in 3% to 5% of patients (2-5). Primary stenting may offer additional benefits. However, a recent meta-analysis of clinical trials found no difference in mortality and reinfarction rates among patients undergoing stenting or balloon angioplasty (6). We conducted a meta-analysis based on published and unpublished trial data to investigate whether primary stenting as compared with balloon angioplasty reduces mortality, recurrent events, and the risk of bleeding in patients with myocardial infarction. METHODS Data Search and Trial Selection We searched MEDLINE, EMBASE, Pascal, Index Medicus, the Cochrane Library, and abstracts from cardiology conferences from 1979 to March 2002 to identify all randomized controlled trials that compared primary stenting with balloon angioplasty in patients with myocardial infarction. We used the following search terms: angioplasty transluminal percutaneous coronary, stents, randomized controlled trials, clinical trials, coronary artery dilatation, transluminal coronary angioplasty, and random. We also searched all references of relevant articles for additional trials. If necessary, authors of identified trials were contacted for additional information

Accuracy of drug advertisements in medical journals under new law regulating the marketing of pharmaceutical products in Switzerland

<p>Abstract</p> <p>Background</p> <p>New legal regulations for the marketing of pharmaceutical products were introduced in 2002 in Switzerland. We investigated whether claims in drug advertisements citing published scientific studies were justified by these studies after the introduction of these new regulations.</p> <p>Methods</p> <p>In this cross-sectional study, two independent reviewers screened all issues of six major Swiss medical journals published in the year 2005 to identify all drug advertisements for analgesic, gastrointestinal and psychopharmacologic drugs and evaluated all drug advertisements referring to at least one publication. The pharmaceutical claim was rated as being supported, being based on a potentially biased study or not to be supported by the cited study according to pre-specified criteria. We also explored factors likely to be associated with supported advertisement claims.</p> <p>Results</p> <p>Of 2068 advertisements 577 (28%) promoted analgesic, psychopharmacologic or gastrointestinal drugs. Among them were 323 (56%) advertisements citing at least one reference. After excluding multiple publications of the same drug advertisement and advertisements with non-informative references, there remained 29 unique advertisements with at least one reference to a scientific study. These 29 advertisements contained 78 distinct pairs of claims of analgesic, gastrointestinal and psychopharmacologic drugs and referenced studies. Thirty-seven (47%) claims were supported, 16 (21%) claims were not supported by the corresponding reference, and 25 (32%) claims were based on potentially biased evidence, with no relevant differences between drug groups. Studies with conflict of interest and studies stating industry funding were more likely to support the corresponding claim (RR 1.52, 95% CI 1.07–2.17 and RR 1.50, 95% CI 0.98–2.28) than studies without identified conflict of interest and studies without information on type of funding.</p> <p>Conclusion</p> <p>Following the introduction of new regulations for drug advertisement in Switzerland, 53% of all assessed pharmaceutical claims published in major medical journals are not supported by the cited referenced studies or based on potentially biased study information. In light of the discrepancy between the new legislation and the endorsement of these regulations, physicians should not trust drug advertisement claims even when they seem to refer to scientific studies.</p

Association between change in high density lipoprotein cholesterol and cardiovascular disease morbidity and mortality: systematic review and meta-regression analysis

Objective To investigate the association between treatment induced change in high density lipoprotein cholesterol and total death, coronary heart disease death, and coronary heart disease events (coronary heart disease death and non-fatal myocardial infarction) adjusted for changes in low density lipoprotein cholesterol and drug class in randomised trials of lipid modifying interventions

Antibody Response After Third Vaccination With mRNA-1273 or BNT162b2: Extension of a Randomized Controlled SARS-CoV-2 Noninferiority Vaccine Trial in Patients With Different Levels of Immunosuppression (COVERALL-2).

Extension of the COVERALL (COrona VaccinE tRiAL pLatform) randomized trial showed noninferiority in antibody response of the third dose of Moderna mRNA-1273 vaccine (95.3% [95% confidence interval {CI}, 91.9%-98.7%]) compared to Pfizer-BioNTech BNT162b2 vaccine (98.1% [95% CI, 95.9%-100.0%]) in individuals with different levels of immunosuppression (difference, -2.8% [95% CI, -6.8% to 1.3%])

Premature Discontinuation of Pediatric Randomized Controlled Trials : A Retrospective Cohort Study

Objectives To determine the proportion of pediatric randomized controlled trials (RCTs) that are prematurely discontinued, examine the reasons for discontinuation, and compare the risk for recruitment failure in pediatric and adult RCTs. Study design A retrospective cohort study of RCTs approved by 1 of 6 Research Ethics Committees (RECs) in Switzerland, Germany, and Canada between 2000 and 2003. We recorded trial characteristics, trial discontinuation, and reasons for discontinuation from protocols, corresponding publications, REC files, and a survey of trialists. Results We included 894 RCTs, of which 86 enrolled children and 808 enrolled adults. Forty percent of the pediatric RCTs and 29% of the adult RCTs were discontinued. Slow recruitment accounted for 56% of pediatric RCT discontinuations and 43% of adult RCT discontinuations. Multivariable logistic regression analyses suggested that pediatric RCT was not an independent risk factor for recruitment failure after adjustment for other potential risk factors (aOR, 1.22; 95% CI, 0.57-2.63). Independent risk factors were acute care setting (aOR, 4.00; 95% CI, 1.72-9.31), nonindustry sponsorship (aOR, 4.45; 95% CI, 2.59-7.65), and smaller planned sample size (aOR, 1.05; 95% CI 1.01-1.09, in decrements of 100 participants). Conclusion Forty percent of pediatric RCTs were discontinued prematurely, owing predominately to slow recruitment. Enrollment of children was not an independent risk factor for recruitment failure.Peer reviewe

Antibody Response After the Third SARS-CoV-2 Vaccine in Solid Organ Transplant Recipients and People Living With HIV (COVERALL-2).

BACKGROUND After basic immunization with 2 mRNA SARS-CoV-2 vaccine doses, only a small proportion of patients who are severely immunocompromised generate a sufficient antibody response. Hence, we assessed the additional benefit of a third SARS-CoV-2 vaccine in patients with different levels of immunosuppression. METHODS In this observational extension of the COVERALL trial (Corona Vaccine Trial Platform), we recruited patients from the Swiss HIV Cohort Study and the Swiss Transplant Cohort Study (ie, lung and kidney transplant recipients). We collected blood samples before and 8 weeks after the third SARS-CoV-2 vaccination with either mRNA-1273 (Moderna) or BNT162b2 (Pfizer-BioNTech). The primary outcome was the proportion of participants showing an antibody response (Elecsys Anti-SARS-CoV-2 S test; threshold ≥100 U/mL) 8 weeks after the third SARS-CoV-2 vaccination. We also compared the proportion of patients who reached the primary outcome from basic immunization (the first and second vaccines) to the third vaccination. RESULTS Nearly all participants (97.2% [95% CI, 95.9%-98.6%], 564/580) had an antibody response. This response was comparable between mRNA-1273 (96.1% [95% CI, 93.7%-98.6%], 245/255) and BNT162b2 (98.2% [95% CI, 96.7%-99.6%], 319/325). Stratification by cohort showed that 99.8% (502/503) of people living with HIV and 80.5% (62/77) of recipients of solid organ transplants achieved the primary endpoint. The proportion of patients with an antibody response in solid organ transplant recipients improved from the second vaccination (22.7%, 15/66) to the third (80.5%, 62/77). CONCLUSIONS People living with HIV had a high antibody response. The third vaccine increased the proportion of solid organ transplant recipients with an antibody response. Clinical Trials Registration. NCT04805125 (ClinicalTrials.gov)