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The purpose of this study is to explore the dependence of material properties and failure criteria for fused deposition modeling (FDM) polycarbonate on raster orientation.

Tension, hardness and density measurements were conducted on a range of specimens at raster angles between 0 and 90° at 15° intervals. Specimens were manufactured so the raster angle was constant throughout each specimen (no rotation between adjacent layers). The yield strength, tensile strength, per cent elongation, elastic modulus, hardness and density of the material were measured as a function of raster angle. The orientation dependence of the properties was then analyzed and used to motivate a failure mechanism map for the material.

The properties of the material were found to be highly orientation-dependent. The variations in mechanical properties were explained to first order using a failure mechanism map similar to those generated for fiber-reinforced composites.

In addition to providing valuable experimental data for FDM polycarbonate, the study proposes micro-mechanisms of failure that appear to explain and capture the angular variation of strength with raster orientation. The fact that analysis methods which have been used for composites appear to apply to FDM materials suggests rich areas for future exploration.

This study aims to identify health workforce challenges at Iranian hospitals during the COVID-19 pandemic.

This was a conventional content analysis study conducted in 2020. The population consisted of the managers (heads of hospitals, managers and matrons) and staff (nurses, physicians, etc.) of eligible hospitals. The participants were selected using purposive sampling, and data saturation was achieved after 28 interviews. The data were analyzed in MAXQDA10.

In total, 28 interviews were conducted with 10 women and 18 men. The challenges of hospital human resources were categorized into five main themes and 15 sub-themes. The main themes were the shortage of human resources, burnout, the need to acquire new knowledge and skills, the employees’ health and safety and the reward system.

Identification of challenges faced by human resources is the first step toward preventing human force shortage and psychological problems in the personnel. Implementing the recommendations of the present study would assist the proper management of hospitals’ human resources.