Erratum: “Transient dynamics and stability of keyhole at threshold in laser powder bed fusion regime investigated by finite element modeling” [J. Laser Appl. 33, 012024 (2021)]

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Transient dynamics and stability of keyhole at threshold in laser powder bed fusion regime investigated by finite element modeling

A Finite element model is developed with a commercial code to investigate the keyhole dynamics and stability at keyhole threshold, a fusion regime characteristic to laser microwelding or to Laser Powder Bed Fusion. The model includes relevant physics to treat the hydrodynamic problems - surface tension, Marangoni stress, and recoil pressure - as well as a self-consistent ray-tracing algorithm to account for the "beam-trapping"effect. Implemented in both static and scanning laser configurations, the model successfully reproduces some key features that most recent x-ray images have exhibited. The dynamics of the liquid/gas interface is analyzed, in line with the distribution of the absorbed intensity as well as with the increase of the keyhole energy coupling. Based on these results, new elements are provided to discuss our current understanding of the keyhole formation and stability at threshold.The authors are grateful to Anthony D. Rollett and Tao Sun for helpful discussion on their x-ray experiments. This work has been supported by Safran Additive Manufacturing and Association Nationale de la Recherche et de la Technology (ANRT)

Cellular and Molecular Mechanisms Underlying the Strong Neonatal IL-12 Response of Lamb Mesenteric Lymph Node Cells to R-848

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An innovative method to assess and manage residual stresses in additively manufactured titanium

A simple method for residual stresses (RS) evaluation in additively manufactured titanium samples is described in this study. This method allows to obtain samples that are separated from the build plate but still include building’s RS. Thanks to these samples, the influence of time and temperature on thermal stress relieving performance and microstructural evolution for Ti64 alloy processed by LBM have been analysed. Additionally, the obtained data allowed to compare the thermal stress relief behaviour of additively manufactured parts to conventional wrought alloy. Process simulations have also been undertaken to predict RS fields and check this method accuracy

Treatment of poststroke anxiety in an older adult male: A single-case analysis

A single-case analysis was carried out to study the nonpharmacological treatment of post-stroke anxiety in an older adult male. The intervention consisted of a biofeedback-assisted program of autogenic training; efficacy was demonstrated using multiple discontinuations and reinstatements of treatment. Physiological indices and self-report measures of anxiety and depression documented treatment success, although a moderate increase in fear was evident on the Fear Survey Schedule II at the final follow-up assessment

A mesoscopic approach for modelling laser beam melting (LBM)

Laser Beam Melting (LBM) is currently garnering industrial attention and many numerical researches have been carried out in order to understand the physics behind the process. However, due to the gap between the grain scale (micrometres) and the bead scale (millimetres), current state-of-the-art multi-physical models are computationally expensive as each powder grain is individually represented. Hence, simulating more than a single LBM track in a reasonable computational time is a challenging task. To overcome this limitation, a new mesoscopic approach is proposed, which intends to bridge the fine thermo-hydrodynamic representation and the macroscopic thermal models. The powder bed is represented by a homogeneous medium with both equivalent thermal and fluid properties. A bulk heat source is considered when the laser heats the powder bed whereas a surface heat flux is imposed on the melted powder bed surface. Apparent viscosity and surface tension are attributed to the homogenized medium so that modelling powder densification, melting and spheroidization of the melt pool is made possible by solving compressible Navier-Stokes equations. In addition, thermocapillary effects as well as vaporisation-induced recoil pressure are implemented, so that realistic thermo-hydrodynamic phenomena are successfully taken into account

Quality of life of adult Fontan patients

International audienceBACKGROUND: Progress in the management of complex congenital heart disease (CHD) led to an improvement in survival rates of adults with a Fontan-like circulation. The objective of this study was to assess the subjective health status and quality of life of this population. METHODS AND RESULTS: Patients aged more than 18 years at the time of the study, who underwent a Fontan-like procedure. Subjective health status was assessed by the SF-36 questionnaire and a linear analog scale was used to score patients' self-perception of their quality of life; cardiac and demographic parameters were collected. RESULTS: Among 65 eligible patients, 60 (23 females; mean ± SD age: 25.7 ± 7.2 years) answered the SF-36 questionnaire and 46 of these were interviewed to evaluate their perceived quality of life. Among them, 20 (33.3%) were working full-time and 21 (35%) experienced arrhythmias. The physical SF-36 scores were lower in patients than in the general population (p ≤ 0.05). The New York Hear Association (NYHA) class and occupation were correlated with SF-36 scores of physical activity (respectively, p = 0.0001 and p = 0.025). SF-36 scores of psychological status were associated with the number of drugs and occupation (respectively, p = 0.0001 and p = 0.02). The mean ± SD quality of life score measured using a linear analog scale was 7.02 ± 1.6 and was linked to education and occupation (p ≤ 0.05) but not with cardiac parameters. CONCLUSION: Adult Fontan patients perceive an impaired physical health but report a good overall quality of life. Education and occupation impacts significantly on Fontan patients' quality of life