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Ablation of atrial tachycardias arising from the superior portion of Crista Terminalis may be risky because of the possibility to injure the right phrenic nerve. Although few techniques for phrenic nerve displacement have been reported, their execution can be difficult, timeconsuming and expose the patient to further complications related to epicardial puncture. In our case, radiofrequency catheter ablation from the right superior pulmonary vein allowed us to successfully treat the arrhythmia without hampering the phrenic nerve integrity. [ABSTRACT FROM AUTHOR]

[Display omitted] Additively Manufactured parts are known to be heavily affected by the 3D-printing parameters, and their layered morphology represents a challenge in the mechanical design analysis for engineering applications. In this work, the fracture mechanics of 3D-printed polylactic acid (PLA) samples along different printing directions was simulated as a laminate composite using different numerical approaches, i.e. extended Finite Element (XFEM) and cohesive method. Tensile specimens were 3D-printed via Fused Filament Fabrication in different directions and tested to build the stiffness matrix needed to define the constitutive behavior of the 3D-printed material. Moreover, the influence of different printing parameters (i.e. printing direction, infill, nozzle temperature and perimeter) on the mechanical response was investigated using the statistical approach analysis of variance (Anova). The statistical analysis has shown a strong influence of the printing direction and the perimeters on the resulting mechanical properties, with tensile strength ranging from 52 MPa in the best case to 4 MPa in the worst. The performed FEM analysis correctly predicts the fracture behavior of the 3D-printed samples, with an error on the predicted failure load well below 7%. The investigated model, thus, represents a useful analysis approach to broader the use of 3D printing in engineering applications. [ABSTRACT FROM AUTHOR]

Puncture resistance has become one of the most requested safety features, not only for protective garments such as stab vests, but also for safety shoes and gloves. Currently, this characteristic is highly demanded in the tyre industry. Conventional protective solutions, such as metallic plates and composite inserts prove to be either bulky or ineffective. The main objective of this work is the design and validation of a novel insert resistant to puncture. This composite insert consisted of a sandwich material with shear-thickening fluid interposed as the core. The dilatancy (shear-thickening) is time-independent rheological behaviour exhibited by some non-Newtonian fluids. These fluids manifest a surge in the apparent viscosity with an increase in the shear rate. In the first part of this work, a comparison between the rheological performance of different shear-thickening fluids (STFs) based on nanosilica dispersed in glycols is presented. This analysis attempts to investigate the combinations of fillers and carriers with the highest energy-absorbing capabilities among various glycol-based colloidal STFs. In the second part, the influence of the composition of the STF on its rheological properties is analyzed statistically. Finally, the puncture resistance of a composite system obtained by encapsulating the previously manufactured shear-thickening fluids in a polymeric shell is analyzed by means of a high-speed puncture test. This test was performed on the mockup of a tyre tread containing the best performing STF. The results showed that the use of the STF core increased the resistance to puncture by 20% as compared to the same volume of tyre tread material. Furthermore, the STF hermetically sealed the pierced sample, even when the tyre mockup was inflated at high internal pressure. [ABSTRACT FROM AUTHOR]

Recent improvements in additive layer manufacturing (ALM) have provided new designs of geometrically complex structures with lighter materials and low processing costs. The use of additive manufacturing in spacecraft production is opening up many new possibilities in both design and fabrication, allowing for the reduction of the weight of the structure subsystems. In this aim, polymeric ALM structures can become a choice, in terms of lightweight and demisability, as far as good thermomechanical properties. Moreover, provided that fused-deposition modeling (FDM) is used, nanosats and other structures could be easily produced in space. However, the choice of the material is a crucial step of the process, as the final performance of the printed parts is strongly dependent on three pillars: design, material, and printing process. As a high-performance technopolymer, polyether ether ketone (PEEK) has been adopted to fabricate parts via ALM; however, the space compatibility of 3D-printed parts remains not demonstrated. This work aimed to realize a nanosat polymeric structure via FDM, including all the phases of the development process: thermomechanical design, raw material selection, printing process tuning, and manufacturing of a proof of concept of a technological model. The design phase includes the application of topology optimization to maximize mass saving and take full advantage of the ALM capability. 3D-printed parts were characterized via thermomechanical tests, outgassing tests of 3D-printed parts are reported confirming the outstanding performance of polyether ether ketone and its potential as a material for structural space application. [ABSTRACT FROM AUTHOR]

Introduction Methods Results Conclusion The dST‐Tiso is a newly proposed electrocardiographic (ECG) marker during Brugada (BrS) type I pattern, that predicts the likelihood of ventricular arrhythmia (VA) inducibility in patients with ajmaline‐induced pattern. The objective of this study was to validate the effectiveness of this criterion using an independent data set.Consecutive patients exhibiting a BrS type I ECG pattern following ajmaline administration underwent programmed ventricular stimulation (PVS). dST‐Tiso interval was measured in all patients and tested as a predictor for positive VA inducibility.Among 128 patients (median age 43 years, 59% male) with drug‐induced BrS type I ECG pattern who underwent PVS, 32 (25.0%) had VA inducibility that required defibrillation. Compared to noninducible subjects, those with positive PVS were more commonly male (81% vs. 51%, p = 0.003), had longer PQ (165 vs. 160 ms, p = 0.016) and dST‐Tiso (310 vs. 230 ms, p < 0.001) intervals, and shorter QT interval (412 vs. 420 ms, p = 0.022). When treated as a continuous variable, dST‐Tiso confirmed significant association with VA inducibility, with an adjusted odds ratio of 1.02 (95% confidence interval: 1.01–1.03, p < 0.001) for each 1 ms increase in duration. A dST‐Tiso interval >300 ms yielded a sensitivity of 75%, a specificity of 86%, and positive and negative predictive values of 69% and 91%, respectively.The validation of the model based on the dST‐Tiso interval >300 ms confirmed its high accuracy in predicting VA inducibility in drug‐induced BrS type I pattern. This straightforward ECG marker might be linked to the extent of the electrical substrate of the disease. [ABSTRACT FROM AUTHOR]

The present paper concerns the additive layer manufacturing of polyether-ether–ketone (PEEK) by means of fused deposition modelling (FDM). PEEK is a high-performance polymer (outstanding mechanical properties, high thermal stability and chemical resistance), suitable for space applications, that, however, due to its semicrystalline nature is difficult to process; moreover, only very few FDM printers suitable for PEEK are currently available on the market. In this paper the results of mechanical (tensile tests), thermal (DSC), microstructural (XRD) and morphological (OM and CT-scans) testing of FDM printed PEEK samples are reported, and some of them compared with that of the extruded filament prior to printing. The results evidence the effect of the process on the printed parts in terms of thermal and mechanical properties including fracture mechanism. Moreover, the impact of printing parameters (as infill and filament deposition pattern) on the final mechanical performance is evidenced too, as it is linked to the resisting cross section. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 24-years-old man with a family history of sudden death was scheduled for sudden cardiac death screening at our Center after an episode of syncope. Topics include the alterations related to generation and/or conduction of action potentials in the cardiac tissue can result in the origin and propagation of cardiac arrhythmias, and the heritable mutations in genes that encode heart ion channels are the underlying cause of arrhythmias.