Development of three directional three-dimensional composite dentures with short glass fiber reinforced methyl methacrylate using fused filament fabrication process

Fiber reinforced additive manufacturing (FRAM) is becoming a subject of great interest in dentistry as it offers opportunities that could be explored in the dental field concerned with the “design and manufacture” of devices. Herein, we evaluated the practicality of FRAM for constructing patient specific and affordable composite denture bases with improved mechanical and clinical properties: polymethylmethacrylate (PMMA) as matrix was reinforced with short glass fibers (SGFs) using the fused filament fabrication (FFF) process. Representative parts for this study, were built with different layer heights (0.2, 0.1, 0.05 mm) and volume fractions (0%, 2.5%, 5%) in three mutually perpendicular directions (0˚ in X-Y plane, 90˚ in X-Y plane, and 90˚ in Z axis), and analyzed for surface roughness (resolution) and mechanical properties (tensile, flexural, compressive properties). Mechanical properties were influenced significantly by printing direction, layer height, and volume fractions; in general, parts with lower layer heights and higher SGFs reinforcement constructed in 0˚ in X-Y plane showed improved mechanical properties and good surface finish. Additional scanning electron microscopy was performed to study the effect of fiber distribution, fiber breakage, fiber accumulation and the adhesion at the interface of the PMMA/SGFs composite materials. The practical implications of the study at a “proof of concept stage” are low-cost manufacturing of highly accurate, lightweight and affordable medical devices with enhanced patient comfort in the long term and improved clinical properties particularly for geriatric use. Keywords: Fiber reinforced additive manufacturing, Fused filament fabrication, Denture base, Composite, layer height, surface roughnes

Robotic design and modelling of medical lower extremity exoskeletons

This study aims to explain the development of the robotic Lower Extremity Exoskeleton (LEE) systems between 1960 and 2019 in chronological order. The scans performed in the exoskeleton system’s design have shown that a modeling program, such as AnyBody, and OpenSim, should be used first to observe the design and software animation, followed by the mechanical development of the system using sensors and motors. Also, the use of OpenSim and AnyBody musculoskeletal system software has been proven to play an essential role in designing the human-exoskeleton by eliminating the high costs and risks of the mechanical designs. Furthermore, these modeling systems can enable rapid optimization of the LEE design by detecting the forces and torques falling on the human muscles

PRINTING PARAMETER OPTIMIZATION OF EXTRUDED METAL PASTE BY RESPONSE SURFACE TECHNIQUE

This research is focused on optimizing printing parameters using the response surface (RS) methodology. When printing parameters are not optimized, the resulting prints contain an unacceptable surface finish, porosity, or the print fails entirely as the lower portion of the print will not be able to withstand the weight of consecutive layers. Printing parameters, layer height, and percent infill were adjusted for the study while material flow rate and print head speed were held constant. RS is a statistical based eigenvalue process that uses data points on a three-dimensional curve to predict and identify local maxima or minima. For this study, RS was used to identify the inflection point where surface finish is optimized. A starting point for the parameters begins with rheological characterization of the paste and geometric modeling (or brute force approach). Once the parameters are able to produce an acceptable surface finish, the RS approach was used to refine printing parameters.Mechanical Engineerin

Service Learning Across Disciplines and Countries

Abstract- Moving local civic engagement across national borders has evolved into the concept of International Service Learning, which combines academic study, civic involvement and cultural emersion to give students a deeper, more meaningful global experience. A team of four faculty members from engineering, management and marketing disciplines designed an International Service Learning course (ISL) for a multi-disciplinary learning environment to enhance teamwork, critical thinking and real-world problem-solving capabilities of students in a global market involving the U.S.A. and Turkey. Students and their counterparts innovatively identified a defined business need in Manisa, Turkey, and then engaged in a grassroots civi

Developing Additively Manufactured Iron Powder-filled PLA Composites

The Low-Cost Metal Material Extrusion (LCMMEX) process has gained attention in recent years to produce metallic parts with complex designs. High Iron concentration composite materials have been extensively researched to improve their properties and functionality for advanced manufacturing applications. This study aims to develop knowledge blocks for producing composite parts with high iron percentages and analyze their physical properties based on print parameters. A rectangular sample is manufactured using the Material Extrusion (MEX) process, with variations in layer height, infill density, and print speed. The investigation shows that a number of parameters affects the change in surface roughness, weight, and dimensional accuracy of the printed parts. Furthermore, an increase in the infill percentage leads to a significant increase in magnetic flux. This research study provides insights into the influence of print parameters on the properties of high-iron-filled composite parts, ideal for high-density applications.Mechanical Engineerin

Kinetic and in silico analysis of thiazolidin-based inhibitors of α-carbonic anhydrase isoenzymes.

Durdagi, Serdar/0000-0002-0426-0905 WOS: 000314531000019 PubMed: 23173744 Carbonic anhydrases (CAs, EC 4.2.1.1) are inhibited by sulfonamides, inorganic anions, phenols, salicylic acid derivatives (acting as drug or prodrugs). A novel class of CA inhibitors (CAIs), interacting with the CA isozymes I and II (cytosolic) in a different manner, is reported here. Kinetic measurements allowed us to identify thiazolidin-based compounds as submicromolar-low micromolar inhibitors of these two CA isozymes. Molecular docking studies of a set of such inhibitors within CA I and II active site allowed us to understand the inhibition mechanism. This new class of inhibitors bind differently compared to other classes of inhibitors known to date: they were found between the phenol-binding site, filling thus the middle of the enzyme cavity

DKD R5-7 STANDARDINA GÖRE ETÜV CİHAZI KALİBRASYONUNUN GERÇEKLEŞTİRİLMESİ

Bu çalışmada,  -90ºC ile 500ºC sıcaklık aralığında çalışan ve hastanelerde sterilizasyon amaçlı kullanılan etüv cihazının kalibrasyonu DKD R5-7 standardına uygun olarak gerçekleştirilmiştir. EA-4/02’de “Kalibrasyonda Ölçüm Belirsizliği için Rehber” belirtilen usule göre ölçüm belirsizliği hesaplanarak kalibrasyon belirsizliğine dahil edilmiştir. Kalibrasyon belirsizliği değerine göre test edilen etüv cihazının ölçüm değerlerinin beyan edilen sınırlar içerisinde olduğu tespit edilmiştir. Ancak yapılan ölçümler etüv içerisindeki ısının homojen dağılmadığını göstermiştir. Sonuç olarak sağlık kuruluşlarında kullanılacak etüv cihazlarında boru tipi ısıtıcı yerine geniş yüzeyli yaprak tipi ısıtıcıların kullanılmasının daha uygun olacağı tespit edilmiştir

Cognitive and motor performances in dual task in patients with chronic obstructive pulmonary disease: a comparative study

Background Patients with chronic obstructive pulmonary disease (COPD) may display a motor and/or cognitive disadvantage during dual tasking. However, studies investigating dual task are quite limited in patients with COPD. Aims To compare cognitive and motor performances (i.e., muscle force production and functional balance/mobility together with a cognitive task) in dual task between patients with COPD and healthy controls. Methods Thirty-five clinically stable patients with COPD and 27 age- and sex-matched healthy controls participated in this cross-sectional controlled study. The muscle force production (knee extension muscle strength assessed with an isokinetic strength dynamometer) and functional balance/mobility (Timed Up and Go (TUG) test) were performed with and without a cognitive task. Dual-task interference (DTI) was assessed. Additionally, the rate of correct responses per second (RCR) was calculated to evaluate cognitive performance. Results The decrease in RCR(muscle force production)values was greater in the COPD group compared with the control group (p= 0.045). Similarly, the cognitive DTI in muscle force production test was higher in the control group than in the COPD group (p 0.05). Conclusion The study results indicate that in individuals with COPD, cognitive performance deteriorations are more pronounced than motor performance defects during dual tasking. Further studies are needed to investigate the effects of dual task taking into account this disadvantage in patients with COPD rather than focusing solely on motor performance

THERMAL SIMULATION OF THE MATERIAL EXTRUSION PROCESS WITH DIFFERENT PRINT BED BOUNDARY CONDITIONS

The temperature evolution in the material extrusion (MEX) process significantly affects the stability and bonding of 3D printed parts. Numerous studies have focused on developing models to capture the temperature history of the MEX process. However, there remains a need to explore the influence of different boundary conditions applied to the print bed. Additionally, the size of the bed relative to the 3D printed object has not been extensively investigated. This study aims to analyze the thermal behavior of the first layer in MEX by considering various boundary conditions and bed sizes. The obtained results will contribute to the development of faster yet reliable models for simulating the temperature variation in the MEX process.Mechanical Engineerin

Fatigue Life Prediction of Functionally Graded TPU and PLA Components Produced by Material Extrusion

The objective of the present research is to examine the fatigue life estimation of functionally graded additive manufacturing (FGAM) components produced by the Material Extrusion (MEX). Current research studies demonstrate the potential of functionally graded materials (FGMs) in enhancing the mechanical properties of engineered structures. The raw materials employed for the experimentation of this study are a combination of Polylactic acid (PLA) and Thermoplastic Polyurethane (TPU). To predict fatigue life, several researchers have utilized various statistical approaches. In this investigation, an experimental study is conducted utilizing Tension-Tension (T-T) loading conditions and different stress levels (80, 60, 40, and 20% of Ultimate tensile strength), followed by the application of Basquin’s Model for fatigue life prediction. The results obtained indicate that the model may be utilized to predict fatigue response. Overall, the soft-hard material combinations with adaptable properties produced through FGAM have potential applications in dental and orthopedic fields.Mechanical Engineerin