Experimental Investigation and Modelling of FDM Process Parameters for Tensile Strength Improvement Using RSM Abstract Fused Deposition Modeling (FDM) is one of the most popular additive manufacturing technologies for various engineering applications. The FDM built part is especially anisotropic in nature due to layer-by-layer building mechanism. Therefore, the mechanical properties, especially the tensile strength severaly depend on the process parameters. Hence, the present work focuses on extensive study to understand the effect of four important parameters such as layer thickness, infill density, printing temperature and wall thickness on the tensile strength of test specimens. A total of 30 test specimens were printed using varying processing parameters according Central Composite Design of experiments (CCD) in order to reduce the experimental runs. The RSM method was used to generate a mathematical model, ie an equation (second order polynomial) which describes the process. Experimental results indicate that the wall thickness and infill density have the significant influence on tensile strength, and tensile strength increases with increasing wall thickeness and infill density. Printing temperature and layer thickness have less of an effect on tensile strength. Tensile strength increases with increasing printing temperature and decreases with increasing in layer thickness, especially at lower printing temperature. This paper examines the influence of selected FDM process parameters (layer thickness, infill density, printing temperature and wall thickness) on the tensile strength of the built parts. Design of experiment for doing the experiments makes use of Circumscribed Central Composite Design (CCCD). Empirical relationship between response and different process parameters is established using RSM, and its validity is checked using ANOVA. The developed relationship between tensile strength (output) and process parameters (input) is able to explain the 91.84% of variability in the response. Effect of various factors and their interactions are explained using response surface plots. It shown that the tensile strength is influenced significantly infill density and wall thickness; and less significantly printing temperature and layer thickness. In order to improve the tensile strength of FDM parts made of PLA materials, it is necessary to increase the infill density and wall thickness, decrease the layer thickness, and set the printing temperature in range 200 – 230 °C. The future research is to investigate the effect of all analyzed parameters on tensile strength for different building directions.

In the XX century, especially after WWII, a great number of ethnic Macedonians have migrated to Australia and the US, while recently, after the 1991 dissolution of Yugoslavia, the direction of the migration influx has changed its course mainly towards Europe. While the first diaspora community was motivated by economic reasons drawing rural and urban citizens alike in pursuit of better life, the second wave of migration was led by political circumstances pushing mostly young educated people who failed to envisage decent life in the homeland. Hence there is a reason to believe that the two communities have different views and feelings of their homeland that underpin their construction of it. To identify the types of ‘Macedonia’ constructed by these two communities of migrants, and trace similarities and differences, this study will analyze on-line discourses on Macedonia produced by the members of the two diasporas. In so doing, we will be particularly interested in the meanings, attitudes, feelings and images the two communities ascribe to the homeland through the on-line interaction on their FB pages.

Dr. Eva Haljecka, a Jew of Polish origin, was born on 1869 in Poland, died on 1949 in Yugoslavia, Belgrade, was the first woman surgeon and gynecologist-obstetrician in Serbia and Yugoslavia. Carried out on 1910 the first caesarean section in Niš. She was a duty manager in district hospital in Niš in three occasions - during the Balkan wars, in the World War I and after the World War I. Dr. Eva Haljecka was the first woman doctor of that time in Serbia who seek the full equality beetween male and female doctors and she was awarded for that. German newspaper Illustrirte Zeitung wrote about her and also about other women doctors - Draga Ljočić, Darinka Maletić-Banković, Marija Vučetić-Prita and Ljubica Đurić. Dr. Eva Haljecka accepted Serbia as a new homeland and made it for her all that he could.

Coronavirus disease 2019 (COVID-19) is a severe infectious disease of the respiratory system with clinical signs of severe acute respiratory syndrome. The causative agent is coronavirus 2 (SARS-CoV-2). Common symptoms of COVID-19 pneumonia are fever, cough, shortness of breath, myalgia, expectoration of sputum and sore throat. The X-ray image of COVID-19 pneumonia has its own characteristics and changes with the evolution of the disease. At the beginning of the disease, the radiological finding in the lungs may be normal or changes may be visualized in the lungs in the form of multiple hazy vaguely delineated shadows, which occur gradually, discreetly and modestly, and in the later stage confluence into larger first irregular patch formations, then they grow into a massive irregular shadow of the intensity of the frosted glass, only to diffusely cover the whole lung. Inflammatory changes are usually bilateral, less often unilateral localization, predominantly in the middle or lower lung field, on the periphery along the chest wall and / or supraphrenic. The aim of this paper is to present an X-ray image of COVID-19 pneumonia and our experiences in the X-ray diagnosis of this disease. The material of the paper consists of selected digital radiographs of the lungs and heart and CT of the lungs with pneumonia COVID-19 in 220 patients, which are during the COVID-19 pandemic from April to July 2020. were examined in covid rendgen CC Niš. The results are presented illustratively. Conclusion: The X-ray examination methods in the diagnosis of COVID-19 pneumonia are sovereign, dominant and unrivaled, and the knowledge of the authors and collaborators and the experience gained through many years of work in the profession and co-X-ray are of crucial importance.

It's common for the syndromes indicate to the author or authors who discovered them. The paper aims to show the image of X-rays and ophthalmic syndrome and to point out to those who can be recognized by the proper radiological and ophthalmologic examination. The work is based on knowledge and experience of the author and co-author of the acquired long experience in the profession, acquired many years of ophthalmology and radiological material, the papers presented in the relevant national and international journals, history and local and foreign literary press. Are shown in - Syndrom Stuger-Weber-Krabbe, Syndrome Wyburn-Mason, Syndrome Von Hippel-Lindau, Syndrome Crouzon, Syndrome Apertand Syndrome Saethre-Chotzen. The authors conclude that ophthalmic syndromes have their own specificity in radiologically-ophthalmologic image.