Influence of an oxygen-free atmosphere on laser beam brazing of aluminium with prior surface deoxidation by pulsed laser radiation

Aluminium alloys, like AlMgSi1 and AlMg3, cannot be joined in industrial processes by laser beam brazing without the use of fluxes due to their resistant oxide layer. The aim of this study is to dispense with the use of flux. For the investigations, an oxygen-free atmosphere was created by using the highly reactive gas monosilane and thus achieving O2 partial pressures of 10-18 mbar. After removal of the oxides by a laser source with 1064 nm wavelength, pulse energies of max. 0.3 µJ and pulse durations of 45 ns, reoxidation is prevented by the oxygen-free atmosphere, so that brazing is carried out on an oxide-free material surface. The bead on plate seams show a materially bonded brazed joint in cross-section. Reference experiments without monosilane either show no wetting or an increased melting of base material. The influence of laser beam power for brazing, pulse energy for deoxidation and wire feed was investigated

ECG findings in professional rugby players using international screening recommendations.

BackgroundWhile World Rugby guidelines do not mandate the inclusion of an electrocardiogram (ECG) for all players, this is required for entry into international rugby competitions. We, therefore, sought to describe sport-specific normative ECG values and evaluate the performance of contemporary athlete ECG guidelines in male and female professional rugby players.MethodsWe retrospectively analysed professional rugby players' ECGs (n=356, male 79%) obtained during preparticipation screening (2010-2022), comparing by sex and playing position (forwards vs backs). ECGs were categorised as normal 'training-related', borderline and abnormal findings, as defined by the 2017 International Recommendations.Results84% of players had one or more normal, 'training-related' findings, with males having a higher prevalence than females (91% vs 60%, pConclusionsThe application of contemporary ECG interpretation criteria resulted in a low positivity rate isolated to male players. These results help inform the logistic feasibility of ECG-inclusive screening, which is already required to enter major tournaments

Association between implanted cardioverter-defibrillators and mortality for patients with left ventricular ejection fraction between 30% and 35%

Background Consensus guidelines support the use of implanted cardioverter-defibrillators (ICD) for primary prevention of sudden cardiac death in patients with either non-ischaemic or ischaemic cardiomyopathy with left ventricular ejection fraction (LVEF) ≤35%. However, evidence from trials for efficacy specifically for patients with LVEF near 35% is weak. Past trials are underpowered for this population and future trials are unlikely to be performed.Methods Patients with lowest LVEF between 30% and 35% without an ICD prior to the lowest-LVEF echo (defined as ‘time zero’) were identified by querying echocardiography data from 28 November 2001 to 9 July 2020 at the Massachusetts General Hospital linked to ICD treatment status. To assess the association between ICD and mortality, propensity score matching followed by Cox proportional hazards models considering treatment status as a time-dependent covariate was used. A secondary analysis was performed for LVEF 36%–40%.Results Initially, 526 440 echocardiograms representing 266 601 unique patients were identified. After inclusion and exclusion criteria were applied, 6109 patients remained for the analytical cohort. In bivariate unadjusted comparisons, patients who received ICDs were substantially more often male (79.8% vs 65.4%, p<0.0001), more often white (87.5% vs 83.7%, p<0.046) and more often had a history of ventricular tachycardia (74.5% vs 19.1%, p<0.0001) and myocardial infarction (56.1% vs 38.2%, p<0.0001). In the propensity matched sample, after accounting for time-dependence, there was no association between ICD and mortality (HR 0.93, 95% CI 0.75 to 1.15, p=0.482).Conclusions ICD therapy was not associated with reduced mortality near the conventional LVEF threshold of 35%. Although this treatment design cannot definitively demonstrate lack of efficacy, our results are concordant with available prior trial data. A definitive, well-powered trial is needed to answer the important clinical question of primary prevention ICD efficacy between LVEF 30% and 35%