Influence of scanning strategy parameters on residual stress in the SLM process according to the Bridge Curvature Method for AISI 316L stainless steel

The present paper deals with the investigation and comparison of the influence of scanning strategy on residual stress in the selective laser melting (SLM) process. For the purpose of the experiment, bridge geometry samples were printed by a 3D metal printer, which exhibited tension after cutting from the substrate, slightly bending the samples toward the laser melting direction. Samples were produced with the variation of process parameters and with a change in scanning strategy which plays a major role in stress generation. It was evaluated using the Bridge Curvature Method (BCM) and optical microscopy. At the end, a recommendation was made.Web of Science137art. no. 165

New Analytical Methods Developed for Determination of Perfluorinated Surfactants in Waters and Wastes

Perfluorinated organic compounds have been recognized in recent years as globally distributed persistent organic pollutants of an entirely anthropogenic origin, but present already even in the most remote places of the globe, including organisms of wild fauna. Numerous studies have also shown that they are contained in human organisms all over the world. In this work a special attention is given to perfluorinated carboxylic acids (PFCAs), widely used in various areas of modern life. New methods developed for their determination using the HPLC with fluorescence detection and capillary electrophoretic methods are discussed, as well as the new method for the determination of total organic fluorine (TOF). (doi: 10.5562/cca1776

Prognostic value of selected risk scales in patients with end-stage heart failure

Background: Due to the increasing number of patients placed on waiting lists for orthotopic heart transplantation (OHT), the selection of patients with the highest risk of death has become paramount.Aim: This study aimed to evaluate the predictive value of the Model for End-stage Liver Disease eXcluding INR (MELD-XI) and Meta-Analysis Global Group in Chronic Heart Failure (MAGGIC) scales in ambulatory patients awaiting OHT and compare them to the Heart Failure Survival Score (HFSS).Methods: The study was a retrospective review of 370 adult ambulatory patients with end-stage heart failure, who were added to the OHT waiting list at our institution between 2012 and 2016.Results: The median age of the patients was 54.0 (46.0–60.0) years, and 324 (87.6%) of them were male. The overall one-year mortality was 27.6%. The areas under the curve (AUCs) for the MAGGIC and HFSS scales were comparable: 0.771 (95% confidence interval [CI] 0.720–0.823); sensitivity 77%, specificity 68% vs. 0.781 (95% CI 0.732–0.829); sensitivity 90%, specificity 58%, respectively. The AUC for the MELD-XI scale was higher than that for the HFSS scale: 0.812 (95% CI 0.769–0.856); sensitivity 91%, specificity 63% vs. 0.781 (95% CI 0.732–0.829) sensitivity 90%, specificity 58%, respectively.Conclusions: Our study demonstrated that elevated MELD-XI and MAGGIC scores and lowered HFSS scores were associated with an increased risk of death during one-year follow-up. The prognostic utility of the MELD-XI scoring system was better than that of the HFSS scale, while the MAGGIC scale was comparable to the HFSS

Effects of equal channel angular pressing and heat treatments on the microstructures and mechanical properties of selective laser melted and cast AlSi10Mg alloys

This study investigated the impact of the equal channel angular pressing (ECAP) combined with heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys fabricated via selective laser melting (SLM) and gravity casting. Special attention was directed towards determining the effect of post-fabrication heat treatments on the microstructural evolution of AlSi10Mg alloy fabricated using two different routes. Three initial alloy conditions were considered prior to ECAP deformation: (1) as-cast in solution treated (T4) condition, (2) SLM in T4 condition, (3) SLM subjected to low-temperature annealing. Light microscopy, transmission electron microscopy, X-ray diffraction line broadening analysis, and electron backscattered diffraction analysis were used to characterize the microstructures before and after ECAP. The results indicated that SLM followed by low-temperature annealing led to superior mechanical properties, relative to the two other conditions. Microscopic analyses revealed that the partial-cellular structure contributed to strong work hardening. This behavior enhanced the material's strength because of the enhanced accumulation of geometrically necessary dislocations during ECAP deformation.Web of Science213art. no. 9

Synthesis of Novel Pyrido[1,2-c]pyrimidine Derivatives with 6-Fluoro-3-(4-piperidynyl)-1,2-benzisoxazole Moiety as Potential SSRI and 5-HT1A Receptor Ligands

Two series of novel 4-aryl-2H-pyrido[1,2-c]pyrimidine (6a–i) and 4-aryl-5,6,7,8-tetrahydropyrido[1,2-c]pyrimidine (7a–i) derivatives were synthesized. The chemical structures of the new compounds were confirmed by 1H and 13C NMR spectroscopy and ESI-HRMS spectrometry. The affinities of all compounds for the 5-HT1A receptor and serotonin transporter protein (SERT) were determined by in vitro radioligand binding assays. The test compounds demonstrated very high binding affinities for the 5-HT1A receptor of all derivatives in the series (6a–i and 7a–i) and generally low binding affinities for the SERT protein, with the exception of compounds 6a and 7g. Extended affinity tests for the receptors D2, 5-HT2A, 5-HT6 and 5-HT7 were conducted with regard to selected compounds (6a, 7g, 6d and 7i). All four compounds demonstrated very high affinities for the D2 and 5-HT2A receptors. Compounds 6a and 7g also had high affinities for 5-HT7, while 6d and 7i held moderate affinities for this receptor. Compounds 6a and 7g were also tested in vivo to identify their functional activity profiles with regard to the 5-HT1A receptor, with 6a demonstrating the activity profile of a presynaptic agonist. Metabolic stability tests were also conducted for 6a and 6d

Mechanical circulatory support restores eligibility for heart transplant in patients with significant pulmonary hypertension

Background: An increasing number of patients with end‑stage heart failure implies a wider use of left ventricular assist devices (LVADs). Irreversible pulmonary hypertension (PH) is a predictor of unfavorable prognosis and a contraindication to orthotopic heart transplant (OHT). Aims: The aim of this study was to evaluate the effect of continuous‑flow LVAD (CF‑LVAD) support on pulmonary pressure and pulmonary vascular resistance (PVR) as well as the impact of pre‑LVAD hemodynamic parameters on survival during LVAD support. Methods: Data collected from 106 patients who underwent CF‑LVAD implantation in the years 2009 to 2018 (men, 95.3%; mean [SD] age, 51.8 [12] years; mean [SD] INTERMACS profile, 2.9 [1.6]; mean [SD] LVAD support time, 661 [520] days; follow‑up until May 2019) were retrospectively analyzed. Results: Right heart catheterization was performed before LVAD implantation in 94 patients (88.7%), after implantation—in 31 (29.2%), and before and after implantation—in 28 (26.4%). We observed mean pulmonary artery pressure (mPAP) > 25 mm Hg in 65 patients (61.3%) and PVR > 2.5 Wood units in 33 patients (31.1%) before LVAD implantation. A significant improvement after CF‑LVAD implantation was noted in mPAP, pulmonary capillary wedge pressure, transpulmonary gradient, PVR, cardiac output (P < 0.001 for all parameters), and cardiac index (P = 0.003). All patients with initially irreversible PH became eligible for OHT during LVAD support. Survival during LVAD support did not depend on initial mPAP and PVR. Conclusions: In patients with end‑stage heart failure, CF‑LVAD support leads to a significant reduction of pre‑ and postcapillary PH. Survival on CF‑LVAD support is independent of elevated mPAP and PVR before implantation, which suggests that LVADs decrease the risk associated with PH