PURPOSE: The objectives of the current study were to estimate the influence of self-reinforced hollow structures with a graded density on the dimensional accuracy, weight, and mechanical properties of Co-Cr objects printed with the direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS: Sixty-five dog-bone samples were manufactured to evaluate the dimensional accuracy of printing, weight, and tensile properties of DMLS printed Co-Cr. They were divided into Group 1 (control) (n = 5), Group 2, 3, and 4 with incorporated hollow structures based on (spherical, elliptical, and diamond) shapes; they were subdivided into subgroups (n = 5) according to the volumetric reduction (10%, 15%, 20% and 25%). Radiographic imaging and microscopic analysis of the fractographs were conducted to validate the created geometries; the dimensional accuracy, weight, yield tensile strength, and modulus of elasticity were calculated. The data were estimated by one-way ANOVA and Duncan’s tests at P < .05. RESULTS: The accuracy test showed an insignificant difference in the x, y, z directions in all printed groups. The weight was significantly reduced proportionally to the reduced volume fraction. The yield strength and elastic modulus of the control group and Group 2 at 10% volume reduction were comparable and significantly higher than the other subgroups. CONCLUSION The printing accuracy was not affected by the presence or type of the hollow geometry. The weight of Group 2 at 10% reduction was significantly lower than that of the control group. The yield strength and elastic modulus of the Group 2 at a 10% reduction showed means equivalent to the compact objects and were significantly higher than other subgroups.

Purpose: Vaccination is a cost-efficient intervention to slow the spread of the coronavirus disease 2019 (COVID-19) pandemic. This study aims to assess the population's willingness to take the COVID-19 vaccine in Jordan and investigate potential determinants of their acceptance Materials and Methods: This study used an online survey distributed in November 2020, before introducing the vaccine, with items investigating socio-demographic characteristics, seasonal flu vaccination history, COVID-19 vaccine acceptance once available, and factors affecting their decision-making. Also, “COVID-19 risk perception” and beliefs toward COVID-19 vaccine benefits and barriers were assessed. Results: A total of 2,208 participants completed the survey with a participation rate of 13.1%. The mean±standard deviation age was 33.2±13.5, and 55.7% were females. Study participants were almost equally distributed between willingness, unwillingness, and indecision to take the COVID-19 vaccine (30.4%, 36.4%, and 31.5%, respectively). Younger adults, males, and those who were not married, do not have children, have a bachelor or higher education, employees or being students, healthcare workers, and those who reported receiving flu vaccine had higher rates of COVID-19 vaccine acceptance compared to their counterparts (p<0.001 for each category). COVID-19 risk perception, and perceived vaccine benefits, and barriers were significant predictors of intention. Among those undecided or unwilling to take the COVID-19 vaccine, its safety and side effects were the most common concerns. Conclusion The low rate of COVID-19 vaccine acceptance in a developing country is alarming, and a significant proportion are indecisive. Interventions to elevate vaccine acceptance by addressing its safety and efficacy and targeting vulnerable groups are recommended.